81364237961 has 2 divisors, whose sum is σ = 81364237962. Its totient is φ = 81364237960.

The previous prime is 81364237891. The next prime is 81364237967. The reversal of 81364237961 is 16973246318.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 76531902736 + 4832335225 = 276644^2 + 69515^2 .

It is a cyclic number.

It is not a de Polignac number, because 81364237961 - 2¹⁸ = 81363975817 is a prime.

It is not a weakly prime, because it can be changed into another prime (81364237967) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40682118980 + 40682118981.

It is an arithmetic number, because the mean of its divisors is an integer number (40682118981).

Almost surely, 2^81364237961 is an apocalyptic number.

It is an amenable number.

81364237961 is a deficient number, since it is larger than the sum of its proper divisors (1).

81364237961 is an equidigital number, since it uses as much as digits as its factorization.

81364237961 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1306368, while the sum is 50.

The spelling of 81364237961 in words is "eighty-one billion, three hundred sixty-four million, two hundred thirty-seven thousand, nine hundred sixty-one".