21172152 has 16 divisors (see below), whose sum is σ = 52930440. Its totient is φ = 7057376.

The previous prime is 21172147. The next prime is 21172153. The reversal of 21172152 is 25127112.

It is a super-2 number, since 2×21172152² = 896520040622208, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21172153) 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, 441063 + ... + 441110.

Almost surely, 2^21172152 is an apocalyptic number.

It is an amenable number.

21172152 is an abundant number, since it is smaller than the sum of its proper divisors (31758288).

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

21172152 is a wasteful number, since it uses less digits than its factorization.

21172152 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 882182 (or 882178 counting only the distinct ones).

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

The square root of 21172152 is about 4601.3206799787. The cubic root of 21172152 is about 276.6442626332.

Adding to 21172152 its reverse (25127112), we get a palindrome (46299264).

The spelling of 21172152 in words is "twenty-one million, one hundred seventy-two thousand, one hundred fifty-two".