21357165 has 16 divisors (see below), whose sum is σ = 34229376. Its totient is φ = 11371200.

The previous prime is 21357107. The next prime is 21357191. The reversal of 21357165 is 56175312.

It is not a de Polignac number, because 21357165 - 2⁶ = 21357101 is a prime.

It is a super-2 number, since 2×21357165² = 912256993674450, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

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, 14775 + ... + 16155.

It is an arithmetic number, because the mean of its divisors is an integer number (2139336).

Almost surely, 2^21357165 is an apocalyptic number.

It is an amenable number.

21357165 is a deficient number, since it is larger than the sum of its proper divisors (12872211).

21357165 is a wasteful number, since it uses less digits than its factorization.

21357165 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2420.

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

The square root of 21357165 is about 4621.3812870180. The cubic root of 21357165 is about 277.4477460250.

The spelling of 21357165 in words is "twenty-one million, three hundred fifty-seven thousand, one hundred sixty-five".