21731408 has 10 divisors (see below), whose sum is σ = 42104634. Its totient is φ = 10865696.

The previous prime is 21731377. The next prime is 21731417. The reversal of 21731408 is 80413712.

It can be written as a sum of positive squares in only one way, i.e., 18731584 + 2999824 = 4328^2 + 1732^2 .

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, 679091 + ... + 679122.

Almost surely, 2^21731408 is an apocalyptic number.

It is an amenable number.

21731408 is a deficient number, since it is larger than the sum of its proper divisors (20373226).

21731408 is a wasteful number, since it uses less digits than its factorization.

21731408 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1358221 (or 1358215 counting only the distinct ones).

The product of its (nonzero) digits is 1344, while the sum is 26.

The square root of 21731408 is about 4661.6958287730. The cubic root of 21731408 is about 279.0589496160.

The spelling of 21731408 in words is "twenty-one million, seven hundred thirty-one thousand, four hundred eight".