77912640 has 168 divisors, whose sum is σ = 288740088. Its totient is φ = 19169280.

The previous prime is 77912633. The next prime is 77912651. The reversal of 77912640 is 4621977.

It is a happy number.

77912640 is a `hidden beast` number, since 7 + 7 + 9 + 1 + 2 + 640 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 331776 + 77580864 = 576^2 + 8808^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a zygodrome in base 12.

It is a junction number, because it is equal to n+sod(n) for n = 77912595 and 77912604.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 36400 + ... + 38480.

It is an arithmetic number, because the mean of its divisors is an integer number (1718691).

Almost surely, 2^77912640 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 77912640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (144370044).

77912640 is an abundant number, since it is smaller than the sum of its proper divisors (210827448).

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

77912640 is a wasteful number, since it uses less digits than its factorization.

77912640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2117 (or 2104 counting only the distinct ones).

The product of its (nonzero) digits is 21168, while the sum is 36.

The square root of 77912640 is about 8826.8136946466. The cubic root of 77912640 is about 427.1062959906.

77912640 divided by its sum of digits (36) gives a triangular number (2164240 = T₂₀₈₀).

The spelling of 77912640 in words is "seventy-seven million, nine hundred twelve thousand, six hundred forty".