77557616640 has 520 divisors, whose sum is σ = 317789831040. Its totient is φ = 17724801024.

The previous prime is 77557616639. The next prime is 77557616641. The reversal of 77557616640 is 4661675577.

77557616640 is a `hidden beast` number, since 7 + 7 + 5 + 576 + 1 + 6 + 64 + 0 = 666.

It is an interprime number because it is at equal distance from previous prime (77557616639) and next prime (77557616641).

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77557616641) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 11608821 + ... + 11615499.

Almost surely, 2^77557616640 is an apocalyptic number.

77557616640 is a gapful number since it is divisible by the number (70) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 77557616640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (158894915520).

77557616640 is an abundant number, since it is smaller than the sum of its proper divisors (240232214400).

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

77557616640 is an equidigital number, since it uses as much as digits as its factorization.

77557616640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6727 (or 6696 counting only the distinct ones).

The product of its (nonzero) digits is 7408800, while the sum is 54.

The spelling of 77557616640 in words is "seventy-seven billion, five hundred fifty-seven million, six hundred sixteen thousand, six hundred forty".