21557332 has 6 divisors (see below), whose sum is σ = 37725338. Its totient is φ = 10778664.

The previous prime is 21557323. The next prime is 21557351. The reversal of 21557332 is 23375512.

It can be written as a sum of positive squares in only one way, i.e., 20034576 + 1522756 = 4476^2 + 1234^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21557332.

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, 2694663 + ... + 2694670.

Almost surely, 2^21557332 is an apocalyptic number.

It is an amenable number.

21557332 is a deficient number, since it is larger than the sum of its proper divisors (16168006).

21557332 is a wasteful number, since it uses less digits than its factorization.

21557332 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5389337 (or 5389335 counting only the distinct ones).

The product of its digits is 6300, while the sum is 28.

The square root of 21557332 is about 4642.9874003706. The cubic root of 21557332 is about 278.3118319971.

The spelling of 21557332 in words is "twenty-one million, five hundred fifty-seven thousand, three hundred thirty-two".