21100172 has 12 divisors (see below), whose sum is σ = 37161600. Its totient is φ = 10482576.

The previous prime is 21100171. The next prime is 21100193. The reversal of 21100172 is 27100112.

It is not an unprimeable number, because it can be changed into a prime (21100171) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16172 + ... + 17427.

It is an arithmetic number, because the mean of its divisors is an integer number (3096800).

Almost surely, 2^21100172 is an apocalyptic number.

It is an amenable number.

21100172 is a deficient number, since it is larger than the sum of its proper divisors (16061428).

21100172 is a wasteful number, since it uses less digits than its factorization.

21100172 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33760 (or 33758 counting only the distinct ones).

The product of its (nonzero) digits is 28, while the sum is 14.

The square root of 21100172 is about 4593.4923533190. The cubic root of 21100172 is about 276.3303996718.

Adding to 21100172 its reverse (27100112), we get a palindrome (48200284).

The spelling of 21100172 in words is "twenty-one million, one hundred thousand, one hundred seventy-two".