21001005100 has 72 divisors (see below), whose sum is σ = 45866987936. Its totient is φ = 8346240000.

The previous prime is 21001005037. The next prime is 21001005173. The reversal of 21001005100 is 150010012.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (10).

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, 15206410 + ... + 15207790.

Almost surely, 2^21001005100 is an apocalyptic number.

21001005100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21001005100 is an abundant number, since it is smaller than the sum of its proper divisors (24865982836).

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

21001005100 is a wasteful number, since it uses less digits than its factorization.

21001005100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2267 (or 2260 counting only the distinct ones).

The product of its (nonzero) digits is 10, while the sum is 10.

Adding to 21001005100 its reverse (150010012), we get a palindrome (21151015112).

The spelling of 21001005100 in words is "twenty-one billion, one million, five thousand, one hundred".