21255330 has 32 divisors (see below), whose sum is σ = 52202304. Its totient is φ = 5535936.

The previous prime is 21255329. The next prime is 21255361. The reversal of 21255330 is 3355212.

It is a junction number, because it is equal to n+sod(n) for n = 21255297 and 21255306.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6949 + ... + 9528.

It is an arithmetic number, because the mean of its divisors is an integer number (1631322).

Almost surely, 2^21255330 is an apocalyptic number.

21255330 is an abundant number, since it is smaller than the sum of its proper divisors (30946974).

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

21255330 is a wasteful number, since it uses less digits than its factorization.

21255330 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16530.

The product of its (nonzero) digits is 900, while the sum is 21.

The square root of 21255330 is about 4610.3503120696. The cubic root of 21255330 is about 277.0060688457.

The spelling of 21255330 in words is "twenty-one million, two hundred fifty-five thousand, three hundred thirty".