78136172820 has 108 divisors (see below), whose sum is σ = 251775284124. Its totient is φ = 19610634240.

The previous prime is 78136172813. The next prime is 78136172839. The reversal of 78136172820 is 2827163187.

78136172820 is a `hidden beast` number, since 7 + 8 + 1 + 3 + 617 + 2 + 8 + 20 = 666.

It can be written as a sum of positive squares in 6 ways, for example, as 753173136 + 77382999684 = 27444^2 + 278178^2 .

It is a super-2 number, since 2×78136172820² (a number of 23 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 699001 + ... + 803040.

Almost surely, 2^78136172820 is an apocalyptic number.

It is an amenable number.

78136172820 is an abundant number, since it is smaller than the sum of its proper divisors (173639111304).

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

78136172820 is a wasteful number, since it uses less digits than its factorization.

78136172820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1502090 (or 1502068 counting only the distinct ones).

The product of its (nonzero) digits is 225792, while the sum is 45.

The spelling of 78136172820 in words is "seventy-eight billion, one hundred thirty-six million, one hundred seventy-two thousand, eight hundred twenty".