77978520 has 48 divisors (see below), whose sum is σ = 253431360. Its totient is φ = 20794176.

The previous prime is 77978503. The next prime is 77978521. The reversal of 77978520 is 2587977.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77978521) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 107944 + ... + 108663.

It is an arithmetic number, because the mean of its divisors is an integer number (5279820).

Almost surely, 2^77978520 is an apocalyptic number.

It is an amenable number.

77978520 is an abundant number, since it is smaller than the sum of its proper divisors (175452840).

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

77978520 is a wasteful number, since it uses less digits than its factorization.

77978520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 216624 (or 216617 counting only the distinct ones).

The product of its (nonzero) digits is 246960, while the sum is 45.

The square root of 77978520 is about 8830.5447170602. The cubic root of 77978520 is about 427.2266437534.

The spelling of 77978520 in words is "seventy-seven million, nine hundred seventy-eight thousand, five hundred twenty".