77809920 has 144 divisors (see below), whose sum is σ = 259604352. Its totient is φ = 19824640.

The previous prime is 77809913. The next prime is 77809931. The reversal of 77809920 is 2990877.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 87880 + ... + 88760.

It is an arithmetic number, because the mean of its divisors is an integer number (1802808).

Almost surely, 2^77809920 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 77809920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (129802176).

77809920 is an abundant number, since it is smaller than the sum of its proper divisors (181794432).

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

77809920 is a wasteful number, since it uses less digits than its factorization.

77809920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 928 (or 914 counting only the distinct ones).

The product of its (nonzero) digits is 63504, while the sum is 42.

The square root of 77809920 is about 8820.9931413645. The cubic root of 77809920 is about 426.9185145074.

The spelling of 77809920 in words is "seventy-seven million, eight hundred nine thousand, nine hundred twenty".