21088530 has 24 divisors (see below), whose sum is σ = 54830412. Its totient is φ = 5623584.

The previous prime is 21088519. The next prime is 21088549. The reversal of 21088530 is 3588012.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 21040569 + 47961 = 4587^2 + 219^2 .

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21088494 and 21088503.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 117069 + ... + 117248.

Almost surely, 2^21088530 is an apocalyptic number.

21088530 is an abundant number, since it is smaller than the sum of its proper divisors (33741882).

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

21088530 is a wasteful number, since it uses less digits than its factorization.

21088530 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 234330 (or 234327 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 27.

The square root of 21088530 is about 4592.2249509361. The cubic root of 21088530 is about 276.2795686428.

The spelling of 21088530 in words is "twenty-one million, eighty-eight thousand, five hundred thirty".