20117978100 has 360 divisors, whose sum is σ = 74243873088. Its totient is φ = 4664563200.

The previous prime is 20117978099. The next prime is 20117978119. The reversal of 20117978100 is 187971102.

It is a super-2 number, since 2×20117978100² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 119 ways as a sum of consecutive naturals, for example, 2044392 + ... + 2054208.

Almost surely, 2^20117978100 is an apocalyptic number.

20117978100 is a gapful number since it is divisible by the number (20) 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 20117978100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37121936544).

20117978100 is an abundant number, since it is smaller than the sum of its proper divisors (54125894988).

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

20117978100 is a wasteful number, since it uses less digits than its factorization.

20117978100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9877 (or 9861 counting only the distinct ones).

The product of its (nonzero) digits is 7056, while the sum is 36.

The spelling of 20117978100 in words is "twenty billion, one hundred seventeen million, nine hundred seventy-eight thousand, one hundred".