77961985920 has 1024 divisors, whose sum is σ = 348039014400. Its totient is φ = 16052649984.

The previous prime is 77961985919. The next prime is 77961985931. The reversal of 77961985920 is 2958916977.

77961985920 is a `hidden beast` number, since 7 + 7 + 9 + 619 + 8 + 5 + 9 + 2 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 67616064 + ... + 67617216.

It is an arithmetic number, because the mean of its divisors is an integer number (339881850).

Almost surely, 2^77961985920 is an apocalyptic number.

77961985920 is a gapful number since it is divisible by the number (70) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 77961985920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (174019507200).

77961985920 is an abundant number, since it is smaller than the sum of its proper divisors (270077028480).

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

77961985920 is a wasteful number, since it uses less digits than its factorization.

77961985920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1244 (or 1226 counting only the distinct ones).

The product of its (nonzero) digits is 17146080, while the sum is 63.

The spelling of 77961985920 in words is "seventy-seven billion, nine hundred sixty-one million, nine hundred eighty-five thousand, nine hundred twenty".