18778493311956 has 144 divisors (see below), whose sum is σ = 54983903694720. Its totient is φ = 5292982713600.

The previous prime is 18778493311939. The next prime is 18778493311957. The reversal of 18778493311956 is 65911339487781.

18778493311956 is a `hidden beast` number, since 1 + 8 + 7 + 78 + 493 + 3 + 1 + 19 + 56 = 666.

It is a super-2 number, since 2×18778493311956² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18778493311957) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 5718435 + ... + 8381973.

Almost surely, 2^{18778493311956} 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 18778493311956, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27491951847360).

18778493311956 is an abundant number, since it is smaller than the sum of its proper divisors (36205410382764).

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

18778493311956 is a wasteful number, since it uses less digits than its factorization.

18778493311956 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2663934 (or 2663929 counting only the distinct ones).

The product of its digits is 274337280, while the sum is 72.

The spelling of 18778493311956 in words is "eighteen trillion, seven hundred seventy-eight billion, four hundred ninety-three million, three hundred eleven thousand, nine hundred fifty-six".