21165357 has 16 divisors (see below), whose sum is σ = 30222720. Its totient is φ = 13128192.

The previous prime is 21165299. The next prime is 21165379. The reversal of 21165357 is 75356112.

It is not a de Polignac number, because 21165357 - 2⁷ = 21165229 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21165457) 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 15 ways as a sum of consecutive naturals, for example, 2208 + ... + 6870.

It is an arithmetic number, because the mean of its divisors is an integer number (1888920).

Almost surely, 2^21165357 is an apocalyptic number.

It is an amenable number.

21165357 is a deficient number, since it is larger than the sum of its proper divisors (9057363).

21165357 is a wasteful number, since it uses less digits than its factorization.

21165357 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4772.

The product of its digits is 6300, while the sum is 30.

The square root of 21165357 is about 4600.5822457598. The cubic root of 21165357 is about 276.6146640217.

The spelling of 21165357 in words is "twenty-one million, one hundred sixty-five thousand, three hundred fifty-seven".