21211572 has 24 divisors (see below), whose sum is σ = 50006656. Its totient is φ = 6997248.

The previous prime is 21211507. The next prime is 21211577. The reversal of 21211572 is 27511212.

It is a super-2 number, since 2×21211572² = 899861573422368, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21211577) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7948 + ... + 10275.

Almost surely, 2^21211572 is an apocalyptic number.

It is an amenable number.

21211572 is an abundant number, since it is smaller than the sum of its proper divisors (28795084).

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

21211572 is a wasteful number, since it uses less digits than its factorization.

21211572 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18327 (or 18325 counting only the distinct ones).

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

The square root of 21211572 is about 4605.6022407498. The cubic root of 21211572 is about 276.8158489650.

Adding to 21211572 its reverse (27511212), we get a palindrome (48722784).

The spelling of 21211572 in words is "twenty-one million, two hundred eleven thousand, five hundred seventy-two".