77991956 has 24 divisors (see below), whose sum is σ = 156198336. Its totient is φ = 33379200.

The previous prime is 77991929. The next prime is 77991983. The reversal of 77991956 is 65919977.

It is an interprime number because it is at equal distance from previous prime (77991929) and next prime (77991983).

It is a junction number, because it is equal to n+sod(n) for n = 77991898 and 77991907.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 25931 + ... + 28781.

It is an arithmetic number, because the mean of its divisors is an integer number (6508264).

Almost surely, 2^77991956 is an apocalyptic number.

It is an amenable number.

77991956 is an abundant number, since it is smaller than the sum of its proper divisors (78206380).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

77991956 is a wasteful number, since it uses less digits than its factorization.

77991956 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3839 (or 3837 counting only the distinct ones).

The product of its digits is 1071630, while the sum is 53.

The square root of 77991956 is about 8831.3054527629. The cubic root of 77991956 is about 427.2511799442.

The spelling of 77991956 in words is "seventy-seven million, nine hundred ninety-one thousand, nine hundred fifty-six".