77991812 has 12 divisors (see below), whose sum is σ = 136549980. Its totient is φ = 38977536.

The previous prime is 77991811. The next prime is 77991821. The reversal of 77991812 is 21819977.

It can be written as a sum of positive squares in 2 ways, for example, as 55562116 + 22429696 = 7454^2 + 4736^2 .

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 (77991811) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10388 + ... + 16244.

It is an arithmetic number, because the mean of its divisors is an integer number (11379165).

Almost surely, 2^77991812 is an apocalyptic number.

It is an amenable number.

77991812 is a deficient number, since it is larger than the sum of its proper divisors (58558168).

77991812 is a wasteful number, since it uses less digits than its factorization.

77991812 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9190 (or 9188 counting only the distinct ones).

The product of its digits is 63504, while the sum is 44.

The square root of 77991812 is about 8831.2972999441. The cubic root of 77991812 is about 427.2509169931.

The spelling of 77991812 in words is "seventy-seven million, nine hundred ninety-one thousand, eight hundred twelve".