191551661056 has 352 divisors, whose sum is σ = 479363512320. Its totient is φ = 74639867904.

The previous prime is 191551661033. The next prime is 191551661069. The reversal of 191551661056 is 650166155191.

It is a junction number, because it is equal to n+sod(n) for n = 191551660997 and 191551661015.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 728333181 + ... + 728333443.

It is an arithmetic number, because the mean of its divisors is an integer number (1361828160).

Almost surely, 2^191551661056 is an apocalyptic number.

191551661056 is a gapful number since it is divisible by the number (16) 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 191551661056, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (239681756160).

191551661056 is an abundant number, since it is smaller than the sum of its proper divisors (287811851264).

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

191551661056 is a wasteful number, since it uses less digits than its factorization.

191551661056 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 489 (or 471 counting only the distinct ones).

The product of its (nonzero) digits is 243000, while the sum is 46.

The spelling of 191551661056 in words is "one hundred ninety-one billion, five hundred fifty-one million, six hundred sixty-one thousand, fifty-six".