81777515012 has 12 divisors (see below), whose sum is σ = 143112713436. Its totient is φ = 40888168320.

The previous prime is 81777515011. The next prime is 81777515023. The reversal of 81777515012 is 21051577718.

It can be written as a sum of positive squares in 2 ways, for example, as 44042898496 + 37734616516 = 209864^2 + 194254^2 .

It is a hoax number, since the sum of its digits (44) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (81777515011) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 356312 + ... + 538992.

It is an arithmetic number, because the mean of its divisors is an integer number (11926059453).

Almost surely, 2^81777515012 is an apocalyptic number.

It is an amenable number.

81777515012 is a deficient number, since it is larger than the sum of its proper divisors (61335198424).

81777515012 is a wasteful number, since it uses less digits than its factorization.

81777515012 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 294598 (or 294596 counting only the distinct ones).

The product of its (nonzero) digits is 137200, while the sum is 44.

The spelling of 81777515012 in words is "eighty-one billion, seven hundred seventy-seven million, five hundred fifteen thousand, twelve".