21864444 has 48 divisors (see below), whose sum is σ = 60845568. Its totient is φ = 5974848.

The previous prime is 21864443. The next prime is 21864457. The reversal of 21864444 is 44446812.

It is a super-2 number, since 2×21864444² = 956107822858272, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21864443) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3727 + ... + 7590.

It is an arithmetic number, because the mean of its divisors is an integer number (1267616).

Almost surely, 2^21864444 is an apocalyptic number.

It is an amenable number.

21864444 is an abundant number, since it is smaller than the sum of its proper divisors (38981124).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21864444 is a wasteful number, since it uses less digits than its factorization.

21864444 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11354 (or 11352 counting only the distinct ones).

The product of its digits is 24576, while the sum is 33.

The square root of 21864444 is about 4675.9431134264. The cubic root of 21864444 is about 279.6272420709.

The spelling of 21864444 in words is "twenty-one million, eight hundred sixty-four thousand, four hundred forty-four".