77978664 has 24 divisors (see below), whose sum is σ = 211192410. Its totient is φ = 25992864.

The previous prime is 77978653. The next prime is 77978689. The reversal of 77978664 is 46687977.

It can be written as a sum of positive squares in only one way, i.e., 69856164 + 8122500 = 8358^2 + 2850^2 .

It is a tau number, because it is divible by the number of its divisors (24).

It is a self number, because there is not a number n which added to its sum of digits gives 77978664.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 541447 + ... + 541590.

Almost surely, 2^77978664 is an apocalyptic number.

It is an amenable number.

77978664 is an abundant number, since it is smaller than the sum of its proper divisors (133213746).

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

77978664 is a wasteful number, since it uses less digits than its factorization.

77978664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1083049 (or 1083042 counting only the distinct ones).

The product of its digits is 3556224, while the sum is 54.

The square root of 77978664 is about 8830.5528705738. The cubic root of 77978664 is about 427.2269067343.

It can be divided in two parts, 7797 and 8664, that added together give a palindrome (16461).

The spelling of 77978664 in words is "seventy-seven million, nine hundred seventy-eight thousand, six hundred sixty-four".