77561880 has 128 divisors (see below), whose sum is σ = 257921280. Its totient is φ = 18501120.

The previous prime is 77561851. The next prime is 77561909. The reversal of 77561880 is 8816577.

It is an interprime number because it is at equal distance from previous prime (77561851) and next prime (77561909).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 88002 + ... + 88878.

It is an arithmetic number, because the mean of its divisors is an integer number (2015010).

Almost surely, 2^77561880 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 77561880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (128960640).

77561880 is an abundant number, since it is smaller than the sum of its proper divisors (180359400).

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

77561880 is a wasteful number, since it uses less digits than its factorization.

77561880 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 969 (or 965 counting only the distinct ones).

The product of its (nonzero) digits is 94080, while the sum is 42.

The square root of 77561880 is about 8806.9222773907. The cubic root of 77561880 is about 426.4643925108.

The spelling of 77561880 in words is "seventy-seven million, five hundred sixty-one thousand, eight hundred eighty".