81377831825 has 12 divisors (see below), whose sum is σ = 101267625228. Its totient is φ = 64870579200.

The previous prime is 81377831803. The next prime is 81377831893. The reversal of 81377831825 is 52813877318.

It is a Cunningham number, because it is equal to 285268²+1.

It can be written as a sum of positive squares in 6 ways, for example, as 1 + 81377831824 = 1^2 + 285268^2 .

It is a de Polignac number, because none of the positive numbers 2^k-81377831825 is a prime.

It is a Duffinian 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, 5784992 + ... + 5799041.

It is an arithmetic number, because the mean of its divisors is an integer number (8438968769).

Almost surely, 2^81377831825 is an apocalyptic number.

It is an amenable number.

81377831825 is a deficient number, since it is larger than the sum of its proper divisors (19889793403).

81377831825 is a wasteful number, since it uses less digits than its factorization.

81377831825 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11584324 (or 11584319 counting only the distinct ones).

The product of its digits is 2257920, while the sum is 53.

The spelling of 81377831825 in words is "eighty-one billion, three hundred seventy-seven million, eight hundred thirty-one thousand, eight hundred twenty-five".