21052172100 has 72 divisors (see below), whose sum is σ = 61251392160. Its totient is φ = 5582535680.

The previous prime is 21052172093. The next prime is 21052172107. The reversal of 21052172100 is 127125012.

It is an interprime number because it is at equal distance from previous prime (21052172093) and next prime (21052172107).

It is not an unprimeable number, because it can be changed into a prime (21052172107) 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, 142317 + ... + 249716.

It is an arithmetic number, because the mean of its divisors is an integer number (850713780).

Almost surely, 2^21052172100 is an apocalyptic number.

21052172100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21052172100 is an abundant number, since it is smaller than the sum of its proper divisors (40199220060).

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

21052172100 is a wasteful number, since it uses less digits than its factorization.

21052172100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 392229 (or 392222 counting only the distinct ones).

The product of its (nonzero) digits is 280, while the sum is 21.

Adding to 21052172100 its reverse (127125012), we get a palindrome (21179297112).

The spelling of 21052172100 in words is "twenty-one billion, fifty-two million, one hundred seventy-two thousand, one hundred".