77661720 has 64 divisors (see below), whose sum is σ = 258876000. Its totient is φ = 20709504.

The previous prime is 77661713. The next prime is 77661743. The reversal of 77661720 is 2716677.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

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

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, 34875 + ... + 37034.

Almost surely, 2^77661720 is an apocalyptic number.

It is an amenable number.

77661720 is an abundant number, since it is smaller than the sum of its proper divisors (181214280).

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

77661720 is a wasteful number, since it uses less digits than its factorization.

77661720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 71929 (or 71919 counting only the distinct ones).

The product of its (nonzero) digits is 24696, while the sum is 36.

The square root of 77661720 is about 8812.5887229576. The cubic root of 77661720 is about 426.6473000107.

The spelling of 77661720 in words is "seventy-seven million, six hundred sixty-one thousand, seven hundred twenty".