21165290 has 24 divisors (see below), whose sum is σ = 39835908. Its totient is φ = 8096000.

The previous prime is 21165271. The next prime is 21165299. The reversal of 21165290 is 9256112.

It can be written as a sum of positive squares in 2 ways, for example, as 18498601 + 2666689 = 4301^2 + 1633^2 .

It is not an unprimeable number, because it can be changed into a prime (21165299) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3290 + ... + 7290.

Almost surely, 2^21165290 is an apocalyptic number.

21165290 is a deficient number, since it is larger than the sum of its proper divisors (18670618).

21165290 is a wasteful number, since it uses less digits than its factorization.

21165290 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4054 (or 4031 counting only the distinct ones).

The product of its (nonzero) digits is 1080, while the sum is 26.

The square root of 21165290 is about 4600.5749640670. The cubic root of 21165290 is about 276.6143721422.

The spelling of 21165290 in words is "twenty-one million, one hundred sixty-five thousand, two hundred ninety".