21863644 has 12 divisors (see below), whose sum is σ = 41739768. Its totient is φ = 9938000.

The previous prime is 21863629. The next prime is 21863657. The reversal of 21863644 is 44636812.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 248407 + ... + 248494.

It is an arithmetic number, because the mean of its divisors is an integer number (3478314).

Almost surely, 2^21863644 is an apocalyptic number.

It is an amenable number.

21863644 is a deficient number, since it is larger than the sum of its proper divisors (19876124).

21863644 is a wasteful number, since it uses less digits than its factorization.

21863644 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 496916 (or 496914 counting only the distinct ones).

The product of its digits is 27648, while the sum is 34.

The square root of 21863644 is about 4675.8575684039. The cubic root of 21863644 is about 279.6238315943.

The spelling of 21863644 in words is "twenty-one million, eight hundred sixty-three thousand, six hundred forty-four".