21571972 has 12 divisors (see below), whose sum is σ = 38098060. Its totient is φ = 10686816.

The previous prime is 21571967. The next prime is 21571987. The reversal of 21571972 is 27917512.

It can be written as a sum of positive squares in 2 ways, for example, as 9834496 + 11737476 = 3136^2 + 3426^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 24303 + ... + 25174.

Almost surely, 2^21571972 is an apocalyptic number.

It is an amenable number.

21571972 is a deficient number, since it is larger than the sum of its proper divisors (16526088).

21571972 is a wasteful number, since it uses less digits than its factorization.

21571972 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 49590 (or 49588 counting only the distinct ones).

The product of its digits is 8820, while the sum is 34.

The square root of 21571972 is about 4644.5637039446. The cubic root of 21571972 is about 278.3748200517.

The spelling of 21571972 in words is "twenty-one million, five hundred seventy-one thousand, nine hundred seventy-two".