81951395775 has 12 divisors (see below), whose sum is σ = 135492974472. Its totient is φ = 43707411040.

The previous prime is 81951395767. The next prime is 81951395819. The reversal of 81951395775 is 57759315918.

It is not a de Polignac number, because 81951395775 - 2³ = 81951395767 is a prime.

It is a Smith number, since the sum of its digits (60) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 546342564 + ... + 546342713.

It is an arithmetic number, because the mean of its divisors is an integer number (11291081206).

Almost surely, 2^81951395775 is an apocalyptic number.

81951395775 is a deficient number, since it is larger than the sum of its proper divisors (53541578697).

81951395775 is a wasteful number, since it uses less digits than its factorization.

81951395775 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1092685290 (or 1092685285 counting only the distinct ones).

The product of its digits is 11907000, while the sum is 60.

The spelling of 81951395775 in words is "eighty-one billion, nine hundred fifty-one million, three hundred ninety-five thousand, seven hundred seventy-five".