77971920 has 160 divisors (see below), whose sum is σ = 264899712. Its totient is φ = 18855936.

The previous prime is 77971897. The next prime is 77971931. The reversal of 77971920 is 2917977.

It is a congruent number.

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, 208854 + ... + 209226.

Almost surely, 2^77971920 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 77971920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (132449856).

77971920 is an abundant number, since it is smaller than the sum of its proper divisors (186927792).

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

77971920 is a wasteful number, since it uses less digits than its factorization.

77971920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 469 (or 463 counting only the distinct ones).

The product of its (nonzero) digits is 55566, while the sum is 42.

The square root of 77971920 is about 8830.1710062716. The cubic root of 77971920 is about 427.2145901118.

The spelling of 77971920 in words is "seventy-seven million, nine hundred seventy-one thousand, nine hundred twenty".