81580945399 has 2 divisors, whose sum is σ = 81580945400. Its totient is φ = 81580945398.

The previous prime is 81580945387. The next prime is 81580945463. The reversal of 81580945399 is 99354908518.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81580945399 - 2²⁷ = 81446727671 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81580945319) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40790472699 + 40790472700.

It is an arithmetic number, because the mean of its divisors is an integer number (40790472700).

Almost surely, 2^81580945399 is an apocalyptic number.

81580945399 is a deficient number, since it is larger than the sum of its proper divisors (1).

81580945399 is an equidigital number, since it uses as much as digits as its factorization.

81580945399 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 13996800, while the sum is 61.

The spelling of 81580945399 in words is "eighty-one billion, five hundred eighty million, nine hundred forty-five thousand, three hundred ninety-nine".