191957981220 has 144 divisors (see below), whose sum is σ = 610064827008. Its totient is φ = 50660951040.

The previous prime is 191957981197. The next prime is 191957981291. The reversal of 191957981220 is 22189759191.

It is a happy number.

191957981220 is a `hidden beast` number, since 191 + 95 + 79 + 81 + 220 = 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 47 ways as a sum of consecutive naturals, for example, 267825 + ... + 675015.

Almost surely, 2^191957981220 is an apocalyptic number.

191957981220 is a gapful number since it is divisible by the number (10) 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 191957981220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (305032413504).

191957981220 is an abundant number, since it is smaller than the sum of its proper divisors (418106845788).

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

191957981220 is a wasteful number, since it uses less digits than its factorization.

191957981220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 407312 (or 407298 counting only the distinct ones).

The product of its (nonzero) digits is 816480, while the sum is 54.

The spelling of 191957981220 in words is "one hundred ninety-one billion, nine hundred fifty-seven million, nine hundred eighty-one thousand, two hundred twenty".