21557372 has 6 divisors (see below), whose sum is σ = 37725408. Its totient is φ = 10778684.

The previous prime is 21557351. The next prime is 21557383. The reversal of 21557372 is 27375512.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2694668 + ... + 2694675.

It is an arithmetic number, because the mean of its divisors is an integer number (6287568).

Almost surely, 2^21557372 is an apocalyptic number.

It is an amenable number.

21557372 is a deficient number, since it is larger than the sum of its proper divisors (16168036).

21557372 is a wasteful number, since it uses less digits than its factorization.

21557372 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5389347 (or 5389345 counting only the distinct ones).

The product of its digits is 14700, while the sum is 32.

The square root of 21557372 is about 4642.9917079400. The cubic root of 21557372 is about 278.3120041344.

The spelling of 21557372 in words is "twenty-one million, five hundred fifty-seven thousand, three hundred seventy-two".