21356365 has 16 divisors (see below), whose sum is σ = 26620416. Its totient is φ = 16430400.

The previous prime is 21356353. The next prime is 21356381. The reversal of 21356365 is 56365312.

It is not a de Polignac number, because 21356365 - 2¹⁷ = 21225293 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (31).

It is a Duffinian number.

Its product of digits (16200) is a multiple of the sum of its prime divisors (900).

It is a congruent number.

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, 32379 + ... + 33031.

It is an arithmetic number, because the mean of its divisors is an integer number (1663776).

Almost surely, 2^21356365 is an apocalyptic number.

It is an amenable number.

21356365 is a deficient number, since it is larger than the sum of its proper divisors (5264051).

21356365 is a wasteful number, since it uses less digits than its factorization.

21356365 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 900.

The product of its digits is 16200, while the sum is 31.

The square root of 21356365 is about 4621.2947319988. The cubic root of 21356365 is about 277.4442817549. Note that the first 3 decimals are identical.

The spelling of 21356365 in words is "twenty-one million, three hundred fifty-six thousand, three hundred sixty-five".