78661739520 has 1408 divisors, whose sum is σ = 355450905600. Its totient is φ = 16148201472.

The previous prime is 78661739503. The next prime is 78661739531. The reversal of 78661739520 is 2593716687.

78661739520 is a `hidden beast` number, since 7 + 86 + 6 + 1 + 7 + 39 + 520 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

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, 2125992942 + ... + 2125992978.

Almost surely, 2^78661739520 is an apocalyptic number.

78661739520 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 78661739520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (177725452800).

78661739520 is an abundant number, since it is smaller than the sum of its proper divisors (276789166080).

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

78661739520 is a wasteful number, since it uses less digits than its factorization.

78661739520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 117 (or 67 counting only the distinct ones).

The product of its (nonzero) digits is 3810240, while the sum is 54.

The spelling of 78661739520 in words is "seventy-eight billion, six hundred sixty-one million, seven hundred thirty-nine thousand, five hundred twenty".