21878572 has 24 divisors (see below), whose sum is σ = 39517632. Its totient is φ = 10592400.

The previous prime is 21878569. The next prime is 21878573. The reversal of 21878572 is 27587812.

It is not an unprimeable number, because it can be changed into a prime (21878573) 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, 22047 + ... + 23017.

It is an arithmetic number, because the mean of its divisors is an integer number (1646568).

Almost surely, 2^21878572 is an apocalyptic number.

It is an amenable number.

21878572 is a deficient number, since it is larger than the sum of its proper divisors (17639060).

21878572 is a wasteful number, since it uses less digits than its factorization.

21878572 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1149 (or 1147 counting only the distinct ones).

The product of its digits is 62720, while the sum is 40.

The square root of 21878572 is about 4677.4535807424. The cubic root of 21878572 is about 279.6874573848.

The spelling of 21878572 in words is "twenty-one million, eight hundred seventy-eight thousand, five hundred seventy-two".