81397699 has 2 divisors, whose sum is σ = 81397700. Its totient is φ = 81397698.

The previous prime is 81397663. The next prime is 81397721. The reversal of 81397699 is 99679318.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81397699 - 2²³ = 73009091 is a prime.

It is not a weakly prime, because it can be changed into another prime (81397399) 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, 40698849 + 40698850.

It is an arithmetic number, because the mean of its divisors is an integer number (40698850).

Almost surely, 2^81397699 is an apocalyptic number.

81397699 is a deficient number, since it is larger than the sum of its proper divisors (1).

81397699 is an equidigital number, since it uses as much as digits as its factorization.

81397699 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 734832, while the sum is 52.

The square root of 81397699 is about 9022.0673351511. The cubic root of 81397699 is about 433.3818402636.

The spelling of 81397699 in words is "eighty-one million, three hundred ninety-seven thousand, six hundred ninety-nine".