21643612 has 6 divisors (see below), whose sum is σ = 37876328. Its totient is φ = 10821804.

The previous prime is 21643607. The next prime is 21643691. The reversal of 21643612 is 21634612.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2705448 + ... + 2705455.

Almost surely, 2^21643612 is an apocalyptic number.

It is an amenable number.

21643612 is a deficient number, since it is larger than the sum of its proper divisors (16232716).

21643612 is a wasteful number, since it uses less digits than its factorization.

21643612 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5410907 (or 5410905 counting only the distinct ones).

The product of its digits is 1728, while the sum is 25.

The square root of 21643612 is about 4652.2695536695. The cubic root of 21643612 is about 278.6826382437.

It can be divided in two parts, 2164 and 3612, that added together give a square (5776 = 76²).

The spelling of 21643612 in words is "twenty-one million, six hundred forty-three thousand, six hundred twelve".