21856396 has 12 divisors (see below), whose sum is σ = 38299240. Its totient is φ = 10913760.

The previous prime is 21856391. The next prime is 21856399. The reversal of 21856396 is 69365812.

It is a super-2 number, since 2×21856396² = 955404092217632, which contains 22 as substring.

It is a hoax number, since the sum of its digits (40) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (21856391) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 256 + ... + 6616.

Almost surely, 2^21856396 is an apocalyptic number.

It is an amenable number.

21856396 is a deficient number, since it is larger than the sum of its proper divisors (16442844).

21856396 is a wasteful number, since it uses less digits than its factorization.

21856396 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7224 (or 7222 counting only the distinct ones).

The product of its digits is 77760, while the sum is 40.

The square root of 21856396 is about 4675.0824591658. The cubic root of 21856396 is about 279.5929288846.

The spelling of 21856396 in words is "twenty-one million, eight hundred fifty-six thousand, three hundred ninety-six".