21578372 has 24 divisors (see below), whose sum is σ = 40190976. Its totient is φ = 10101888.

The previous prime is 21578371. The next prime is 21578383. The reversal of 21578372 is 27387512.

It is a super-2 number, since 2×21578372² = 931252276340768, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21578371) 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, 14453 + ... + 15875.

It is an arithmetic number, because the mean of its divisors is an integer number (1674624).

Almost surely, 2^21578372 is an apocalyptic number.

It is an amenable number.

21578372 is a deficient number, since it is larger than the sum of its proper divisors (18612604).

21578372 is a wasteful number, since it uses less digits than its factorization.

21578372 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1667 (or 1665 counting only the distinct ones).

The product of its digits is 23520, while the sum is 35.

The square root of 21578372 is about 4645.2526303744. The cubic root of 21578372 is about 278.4023468611.

It can be divided in two parts, 215 and 78372, that added together give a palindrome (78587).

The spelling of 21578372 in words is "twenty-one million, five hundred seventy-eight thousand, three hundred seventy-two".