77915520 has 224 divisors, whose sum is σ = 280944720. Its totient is φ = 20653056.

The previous prime is 77915507. The next prime is 77915521. The reversal of 77915520 is 2551977.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77915521) by changing a digit.

It is a polite number, since it can be written in 27 ways as a sum of consecutive naturals, for example, 466477 + ... + 466643.

Almost surely, 2^77915520 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 77915520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (140472360).

77915520 is an abundant number, since it is smaller than the sum of its proper divisors (203029200).

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

77915520 is an equidigital number, since it uses as much as digits as its factorization.

77915520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 204 (or 177 counting only the distinct ones).

The product of its (nonzero) digits is 22050, while the sum is 36.

The square root of 77915520 is about 8826.9768324155. The cubic root of 77915520 is about 427.1115585127. Note that the first 3 decimals are identical.

The spelling of 77915520 in words is "seventy-seven million, nine hundred fifteen thousand, five hundred twenty".