21312823 has 8 divisors (see below), whose sum is σ = 24651648. Its totient is φ = 18047544.

The previous prime is 21312793. The next prime is 21312829. The reversal of 21312823 is 32821312.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21312823 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21312794 and 21312803.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21312829) 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 7 ways as a sum of consecutive naturals, for example, 17761 + ... + 18922.

It is an arithmetic number, because the mean of its divisors is an integer number (3081456).

Almost surely, 2^21312823 is an apocalyptic number.

21312823 is a deficient number, since it is larger than the sum of its proper divisors (3338825).

21312823 is an equidigital number, since it uses as much as digits as its factorization.

21312823 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36773.

The product of its digits is 576, while the sum is 22.

The square root of 21312823 is about 4616.5813108836. The cubic root of 21312823 is about 277.2555995479.

The spelling of 21312823 in words is "twenty-one million, three hundred twelve thousand, eight hundred twenty-three".