21021221012100 has 72 divisors (see below), whose sum is σ = 60836241127200. Its totient is φ = 5604291041280.

The previous prime is 21021221012089. The next prime is 21021221012101. The reversal of 21021221012100 is 121012212012.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 21021221012100.

It is not an unprimeable number, because it can be changed into a prime (21021221012101) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 7317597 + ... + 9776996.

Almost surely, 2^{21021221012100} is an apocalyptic number.

21021221012100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21021221012100 is an abundant number, since it is smaller than the sum of its proper divisors (39815020115100).

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

21021221012100 is a wasteful number, since it uses less digits than its factorization.

21021221012100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17098709 (or 17098702 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 15.

Adding to 21021221012100 its reverse (121012212012), we get a palindrome (21142233224112).

The spelling of 21021221012100 in words is "twenty-one trillion, twenty-one billion, two hundred twenty-one million, twelve thousand, one hundred".