21638696 has 8 divisors (see below), whose sum is σ = 40572570. Its totient is φ = 10819344.

The previous prime is 21638689. The next prime is 21638719. The reversal of 21638696 is 69683612.

It can be written as a sum of positive squares in only one way, i.e., 17757796 + 3880900 = 4214^2 + 1970^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1352411 + ... + 1352426.

Almost surely, 2^21638696 is an apocalyptic number.

It is an amenable number.

21638696 is a deficient number, since it is larger than the sum of its proper divisors (18933874).

21638696 is a wasteful number, since it uses less digits than its factorization.

21638696 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2704843 (or 2704839 counting only the distinct ones).

The product of its digits is 93312, while the sum is 41.

The square root of 21638696 is about 4651.7411793865. The cubic root of 21638696 is about 278.6615372127.

The spelling of 21638696 in words is "twenty-one million, six hundred thirty-eight thousand, six hundred ninety-six".