77978640 has 160 divisors (see below), whose sum is σ = 255983616. Its totient is φ = 19607040.

The previous prime is 77978639. The next prime is 77978653. The reversal of 77978640 is 4687977.

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a self number, because there is not a number n which added to its sum of digits gives 77978640.

It is an unprimeable number.

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 31 ways as a sum of consecutive naturals, for example, 349569 + ... + 349791.

Almost surely, 2^77978640 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 77978640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (127991808).

77978640 is an abundant number, since it is smaller than the sum of its proper divisors (178004976).

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

77978640 is a wasteful number, since it uses less digits than its factorization.

77978640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 317 (or 311 counting only the distinct ones).

The product of its (nonzero) digits is 592704, while the sum is 48.

The square root of 77978640 is about 8830.5515116554. The cubic root of 77978640 is about 427.2268629042.

The spelling of 77978640 in words is "seventy-seven million, nine hundred seventy-eight thousand, six hundred forty".