21645772 has 12 divisors (see below), whose sum is σ = 37922416. Its totient is φ = 10810800.

The previous prime is 21645761. The next prime is 21645787. The reversal of 21645772 is 27754612.

It is a hoax number, since the sum of its digits (34) coincides with the sum of the digits of its distinct prime factors.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1897 + ... + 6847.

Almost surely, 2^21645772 is an apocalyptic number.

It is an amenable number.

21645772 is a deficient number, since it is larger than the sum of its proper divisors (16276644).

21645772 is a wasteful number, since it uses less digits than its factorization.

21645772 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6048 (or 6046 counting only the distinct ones).

The product of its digits is 23520, while the sum is 34.

The square root of 21645772 is about 4652.5016926381. The cubic root of 21645772 is about 278.6919086384.

The spelling of 21645772 in words is "twenty-one million, six hundred forty-five thousand, seven hundred seventy-two".