77431680 has 128 divisors (see below), whose sum is σ = 274298400. Its totient is φ = 20643840.

The previous prime is 77431667. The next prime is 77431687. The reversal of 77431680 is 8613477.

It is a tau number, because it is divible by the number of its divisors (128).

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 (77431687) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 15040 + ... + 19520.

Almost surely, 2^77431680 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 77431680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (137149200).

77431680 is an abundant number, since it is smaller than the sum of its proper divisors (196866720).

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

77431680 is a wasteful number, since it uses less digits than its factorization.

77431680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4509 (or 4491 counting only the distinct ones).

The product of its (nonzero) digits is 28224, while the sum is 36.

The square root of 77431680 is about 8799.5272600294. The cubic root of 77431680 is about 426.2256293345.

The spelling of 77431680 in words is "seventy-seven million, four hundred thirty-one thousand, six hundred eighty".