21901172 has 6 divisors (see below), whose sum is σ = 38327058. Its totient is φ = 10950584.

The previous prime is 21901171. The next prime is 21901183. The reversal of 21901172 is 27110912.

It can be written as a sum of positive squares in only one way, i.e., 15570916 + 6330256 = 3946^2 + 2516^2 .

It is a super-2 number, since 2×21901172² = 959322669947168, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21901171) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2737643 + ... + 2737650.

It is an arithmetic number, because the mean of its divisors is an integer number (6387843).

Almost surely, 2^21901172 is an apocalyptic number.

It is an amenable number.

21901172 is a deficient number, since it is larger than the sum of its proper divisors (16425886).

21901172 is a wasteful number, since it uses less digits than its factorization.

21901172 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5475297 (or 5475295 counting only the distinct ones).

The product of its (nonzero) digits is 252, while the sum is 23.

The square root of 21901172 is about 4679.8688015798. The cubic root of 21901172 is about 279.7837275516.

The spelling of 21901172 in words is "twenty-one million, nine hundred one thousand, one hundred seventy-two".