81399435947 has 2 divisors, whose sum is σ = 81399435948. Its totient is φ = 81399435946.

The previous prime is 81399435937. The next prime is 81399436003. The reversal of 81399435947 is 74953499318.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81399435947 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81399435947.

It is not a weakly prime, because it can be changed into another prime (81399435917) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40699717973 + 40699717974.

It is an arithmetic number, because the mean of its divisors is an integer number (40699717974).

Almost surely, 2^81399435947 is an apocalyptic number.

81399435947 is a deficient number, since it is larger than the sum of its proper divisors (1).

81399435947 is an equidigital number, since it uses as much as digits as its factorization.

81399435947 is an evil number, because the sum of its binary digits is even.

The product of its digits is 29393280, while the sum is 62.

The spelling of 81399435947 in words is "eighty-one billion, three hundred ninety-nine million, four hundred thirty-five thousand, nine hundred forty-seven".