Why 20 digits of number it generate like long

[jack5505]

Hello guys. here is example of why 20 digits of number. Xsd generates it like long type data
40700810256895634168
040037470
1
After using XsdGen class it outputs like this.
xsd:sequence
<xsd:element name="account" minOccurs="0" type="xsd:long"/>
<xsd:element name="branchBIC" minOccurs="0" type="xsd:int"/>
<xsd:element name="branchCode" minOccurs="0" type="xsd:int"/>
<xsd:element name="currencyIsoCode" minOccurs="0" type="xsd:normalizedString"/>
</xsd:sequence>
If you guys pay attention leading zero type is also xsd int and account which more than long maximal size also xsd:long type why not making it string guys.