21668396 has 6 divisors (see below), whose sum is σ = 37919700. Its totient is φ = 10834196.

The previous prime is 21668389. The next prime is 21668401. The reversal of 21668396 is 69386612.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2708546 + ... + 2708553.

It is an arithmetic number, because the mean of its divisors is an integer number (6319950).

Almost surely, 2^21668396 is an apocalyptic number.

It is an amenable number.

21668396 is a deficient number, since it is larger than the sum of its proper divisors (16251304).

21668396 is a wasteful number, since it uses less digits than its factorization.

21668396 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5417103 (or 5417101 counting only the distinct ones).

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

The square root of 21668396 is about 4654.9324377482. The cubic root of 21668396 is about 278.7889704006.

The spelling of 21668396 in words is "twenty-one million, six hundred sixty-eight thousand, three hundred ninety-six".