21312012077 has 2 divisors, whose sum is σ = 21312012078. Its totient is φ = 21312012076.

The previous prime is 21312012049. The next prime is 21312012119. The reversal of 21312012077 is 77021021312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14270452681 + 7041559396 = 119459^2 + 83914^2 .

It is a cyclic number.

It is not a de Polignac number, because 21312012077 - 2⁸ = 21312011821 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21312012047) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10656006038 + 10656006039.

It is an arithmetic number, because the mean of its divisors is an integer number (10656006039).

Almost surely, 2^21312012077 is an apocalyptic number.

It is an amenable number.

21312012077 is a deficient number, since it is larger than the sum of its proper divisors (1).

21312012077 is an equidigital number, since it uses as much as digits as its factorization.

21312012077 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1176, while the sum is 26.

Adding to 21312012077 its reverse (77021021312), we get a palindrome (98333033389).

The spelling of 21312012077 in words is "twenty-one billion, three hundred twelve million, twelve thousand, seventy-seven".