21312877 has 2 divisors, whose sum is σ = 21312878. Its totient is φ = 21312876.

The previous prime is 21312871. The next prime is 21312887. The reversal of 21312877 is 77821312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11162281 + 10150596 = 3341^2 + 3186^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21312877 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21312871) 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 as a sum of consecutive naturals, namely, 10656438 + 10656439.

It is an arithmetic number, because the mean of its divisors is an integer number (10656439).

Almost surely, 2^21312877 is an apocalyptic number.

It is an amenable number.

21312877 is a deficient number, since it is larger than the sum of its proper divisors (1).

21312877 is an equidigital number, since it uses as much as digits as its factorization.

21312877 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4704, while the sum is 31.

The square root of 21312877 is about 4616.5871593635. The cubic root of 21312877 is about 277.2558337072.

The spelling of 21312877 in words is "twenty-one million, three hundred twelve thousand, eight hundred seventy-seven".