21589972 has 6 divisors (see below), whose sum is σ = 37782458. Its totient is φ = 10794984.

The previous prime is 21589961. The next prime is 21589973. The reversal of 21589972 is 27998512.

It can be written as a sum of positive squares in only one way, i.e., 21399876 + 190096 = 4626^2 + 436^2 .

It is a super-2 number, since 2×21589972² = 932253781921568, which contains 22 as substring.

It is a plaindrome in base 9.

It is a zygodrome in base 9.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21589973) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2698743 + ... + 2698750.

Almost surely, 2^21589972 is an apocalyptic number.

It is an amenable number.

21589972 is a deficient number, since it is larger than the sum of its proper divisors (16192486).

21589972 is a wasteful number, since it uses less digits than its factorization.

21589972 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5397497 (or 5397495 counting only the distinct ones).

The product of its digits is 90720, while the sum is 43.

The square root of 21589972 is about 4646.5010491767. The cubic root of 21589972 is about 278.4522253336.

The spelling of 21589972 in words is "twenty-one million, five hundred eighty-nine thousand, nine hundred seventy-two".