77820155136 has 126 divisors (see below), whose sum is σ = 232898505770. Its totient is φ = 25939989504.

The previous prime is 77820155117. The next prime is 77820155143. The reversal of 77820155136 is 63155102877.

It is a happy number.

77820155136 is a `hidden beast` number, since 7 + 78 + 20 + 1 + 551 + 3 + 6 = 666.

It can be written as a sum of positive squares in only one way, i.e., 58107995136 + 19712160000 = 241056^2 + 140400^2 .

It is a super-2 number, since 2×77820155136² (a number of 23 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 77820155091 and 77820155100.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 13 ways as a sum of consecutive naturals, for example, 21871 + ... + 395118.

Almost surely, 2^77820155136 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 77820155136, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (116449252885).

77820155136 is an abundant number, since it is smaller than the sum of its proper divisors (155078350634).

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

77820155136 is an frugal number, since it uses more digits than its factorization.

77820155136 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 417023 (or 416994 counting only the distinct ones).

The product of its (nonzero) digits is 352800, while the sum is 45.

The spelling of 77820155136 in words is "seventy-seven billion, eight hundred twenty million, one hundred fifty-five thousand, one hundred thirty-six".