21456365 has 16 divisors (see below), whose sum is σ = 30028800. Its totient is φ = 14711760.

The previous prime is 21456349. The next prime is 21456373. The reversal of 21456365 is 56365412.

It is not a de Polignac number, because 21456365 - 2⁴ = 21456349 is a prime.

It is an alternating number because its digits alternate between even and odd.

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, 4541 + ... + 7970.

It is an arithmetic number, because the mean of its divisors is an integer number (1876800).

Almost surely, 2^21456365 is an apocalyptic number.

It is an amenable number.

21456365 is a deficient number, since it is larger than the sum of its proper divisors (8572435).

21456365 is an equidigital number, since it uses as much as digits as its factorization.

21456365 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12537 (or 12523 counting only the distinct ones).

The product of its digits is 21600, while the sum is 32.

The square root of 21456365 is about 4632.1015748794. The cubic root of 21456365 is about 277.8766467907.

It can be divided in two parts, 2145 and 6365, that multiplied together give a triangular number (13652925 = T₅₂₂₅).

The spelling of 21456365 in words is "twenty-one million, four hundred fifty-six thousand, three hundred sixty-five".