21813884 has 6 divisors (see below), whose sum is σ = 38174304. Its totient is φ = 10906940.

The previous prime is 21813877. The next prime is 21813931. The reversal of 21813884 is 48831812.

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, 2726732 + ... + 2726739.

It is an arithmetic number, because the mean of its divisors is an integer number (6362384).

Almost surely, 2^21813884 is an apocalyptic number.

It is an amenable number.

21813884 is a deficient number, since it is larger than the sum of its proper divisors (16360420).

21813884 is a wasteful number, since it uses less digits than its factorization.

21813884 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5453475 (or 5453473 counting only the distinct ones).

The product of its digits is 12288, while the sum is 35.

The square root of 21813884 is about 4670.5335883601. The cubic root of 21813884 is about 279.4115362266.

The spelling of 21813884 in words is "twenty-one million, eight hundred thirteen thousand, eight hundred eighty-four".