21713408 has 20 divisors (see below), whose sum is σ = 43385430. Its totient is φ = 10856448.

The previous prime is 21713407. The next prime is 21713443. The reversal of 21713408 is 80431712.

21713408 is nontrivially palindromic in base 7.

It can be written as a sum of positive squares in only one way, i.e., 16908544 + 4804864 = 4112^2 + 2192^2 .

It is not an unprimeable number, because it can be changed into a prime (21713407) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20693 + ... + 21716.

Almost surely, 2^21713408 is an apocalyptic number.

It is an amenable number.

21713408 is a deficient number, since it is larger than the sum of its proper divisors (21672022).

21713408 is an frugal number, since it uses more digits than its factorization.

21713408 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42427 (or 42411 counting only the distinct ones).

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

The square root of 21713408 is about 4659.7648009315. The cubic root of 21713408 is about 278.9818806936.

The spelling of 21713408 in words is "twenty-one million, seven hundred thirteen thousand, four hundred eight".