21312793 has 2 divisors, whose sum is σ = 21312794. Its totient is φ = 21312792.

The previous prime is 21312787. The next prime is 21312829. The reversal of 21312793 is 39721312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15705369 + 5607424 = 3963^2 + 2368^2 .

It is a cyclic number.

It is not a de Polignac number, because 21312793 - 2²¹ = 19215641 is a prime.

It is not a weakly prime, because it can be changed into another prime (21312763) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10656396 + 10656397.

It is an arithmetic number, because the mean of its divisors is an integer number (10656397).

Almost surely, 2^21312793 is an apocalyptic number.

It is an amenable number.

21312793 is a deficient number, since it is larger than the sum of its proper divisors (1).

21312793 is an equidigital number, since it uses as much as digits as its factorization.

21312793 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2268, while the sum is 28.

The square root of 21312793 is about 4616.5780617249. The cubic root of 21312793 is about 277.2554694592.

The spelling of 21312793 in words is "twenty-one million, three hundred twelve thousand, seven hundred ninety-three".