21845916 has 24 divisors (see below), whose sum is σ = 56637840. Its totient is φ = 7281936.

The previous prime is 21845909. The next prime is 21845959. The reversal of 21845916 is 61954812.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 101031 + ... + 101246.

It is an arithmetic number, because the mean of its divisors is an integer number (2359910).

Almost surely, 2^21845916 is an apocalyptic number.

It is an amenable number.

21845916 is an abundant number, since it is smaller than the sum of its proper divisors (34791924).

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

21845916 is a wasteful number, since it uses less digits than its factorization.

21845916 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 202290 (or 202282 counting only the distinct ones).

The product of its digits is 17280, while the sum is 36.

The square root of 21845916 is about 4673.9614889299. The cubic root of 21845916 is about 279.5482340754.

It can be divided in two parts, 2184 and 5916, that added together give a square (8100 = 90²).

The spelling of 21845916 in words is "twenty-one million, eight hundred forty-five thousand, nine hundred sixteen".