81364939 has 2 divisors, whose sum is σ = 81364940. Its totient is φ = 81364938.

The previous prime is 81364919. The next prime is 81364949. The reversal of 81364939 is 93946318.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81364939 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 81364895 and 81364904.

It is not a weakly prime, because it can be changed into another prime (81364919) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40682469 + 40682470.

It is an arithmetic number, because the mean of its divisors is an integer number (40682470).

Almost surely, 2^81364939 is an apocalyptic number.

81364939 is a deficient number, since it is larger than the sum of its proper divisors (1).

81364939 is an equidigital number, since it uses as much as digits as its factorization.

81364939 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 139968, while the sum is 43.

The square root of 81364939 is about 9020.2516040297. The cubic root of 81364939 is about 433.3236916329.

The spelling of 81364939 in words is "eighty-one million, three hundred sixty-four thousand, nine hundred thirty-nine".