21000100100 has 72 divisors (see below), whose sum is σ = 52963068480. Its totient is φ = 7077985920.

The previous prime is 21000100097. The next prime is 21000100111. The reversal of 21000100100 is 100100012.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (5).

21000100100 is a modest number, since divided by 100100 gives 21000 as remainder.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 212939 + ... + 295538.

Almost surely, 2^21000100100 is an apocalyptic number.

21000100100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21000100100 is an abundant number, since it is smaller than the sum of its proper divisors (31962968380).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21000100100 is a wasteful number, since it uses less digits than its factorization.

21000100100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 508557 (or 508550 counting only the distinct ones).

The product of its (nonzero) digits is 2, while the sum is 5.

Adding to 21000100100 its reverse (100100012), we get a palindrome (21100200112).

The spelling of 21000100100 in words is "twenty-one billion, one hundred thousand, one hundred".