21881088 has 54 divisors (see below), whose sum is σ = 63095214. Its totient is φ = 7292928.

The previous prime is 21881087. The next prime is 21881089. The reversal of 21881088 is 88018812.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21881087) and next prime (21881089).

It can be written as a sum of positive squares in only one way, i.e., 13307904 + 8573184 = 3648^2 + 2928^2 .

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21881087) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 2445 + ... + 7052.

Almost surely, 2^21881088 is an apocalyptic number.

It is an amenable number.

21881088 is an abundant number, since it is smaller than the sum of its proper divisors (41214126).

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

21881088 is an equidigital number, since it uses as much as digits as its factorization.

21881088 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9519 (or 9502 counting only the distinct ones).

The product of its (nonzero) digits is 8192, while the sum is 36.

The square root of 21881088 is about 4677.7225227668. The cubic root of 21881088 is about 279.6981781739.

The spelling of 21881088 in words is "twenty-one million, eight hundred eighty-one thousand, eighty-eight".