21375990 has 48 divisors (see below), whose sum is σ = 56113200. Its totient is φ = 5645376.

The previous prime is 21375971. The next prime is 21376009. The reversal of 21375990 is 9957312.

It is an interprime number because it is at equal distance from previous prime (21375971) and next prime (21376009).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 8721 + ... + 10899.

It is an arithmetic number, because the mean of its divisors is an integer number (1169025).

Almost surely, 2^21375990 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21375990, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28056600).

21375990 is an abundant number, since it is smaller than the sum of its proper divisors (34737210).

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

21375990 is a wasteful number, since it uses less digits than its factorization.

21375990 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2301 (or 2298 counting only the distinct ones).

The product of its (nonzero) digits is 17010, while the sum is 36.

The square root of 21375990 is about 4623.4175671250. The cubic root of 21375990 is about 277.5292396752.

The spelling of 21375990 in words is "twenty-one million, three hundred seventy-five thousand, nine hundred ninety".