21265823 has 4 divisors (see below), whose sum is σ = 22190448. Its totient is φ = 20341200.

The previous prime is 21265819. The next prime is 21265831. The reversal of 21265823 is 32856212.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 21265823 - 2² = 21265819 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21265873) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 462278 + ... + 462323.

It is an arithmetic number, because the mean of its divisors is an integer number (5547612).

Almost surely, 2^21265823 is an apocalyptic number.

21265823 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

21265823 is a deficient number, since it is larger than the sum of its proper divisors (924625).

21265823 is an equidigital number, since it uses as much as digits as its factorization.

21265823 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 924624.

The product of its digits is 5760, while the sum is 29.

The square root of 21265823 is about 4611.4881545983. The cubic root of 21265823 is about 277.0516440264.

The spelling of 21265823 in words is "twenty-one million, two hundred sixty-five thousand, eight hundred twenty-three".