191557640 has 16 divisors (see below), whose sum is σ = 431004780. Its totient is φ = 76623040.

The previous prime is 191557631. The next prime is 191557643. The reversal of 191557640 is 46755191.

It can be written as a sum of positive squares in 2 ways, for example, as 191379556 + 178084 = 13834^2 + 422^2 .

It is a junction number, because it is equal to n+sod(n) for n = 191557594 and 191557603.

It is not an unprimeable number, because it can be changed into a prime (191557643) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2394431 + ... + 2394510.

Almost surely, 2^191557640 is an apocalyptic number.

191557640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

191557640 is an abundant number, since it is smaller than the sum of its proper divisors (239447140).

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

191557640 is a wasteful number, since it uses less digits than its factorization.

191557640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4788952 (or 4788948 counting only the distinct ones).

The product of its (nonzero) digits is 37800, while the sum is 38.

The square root of 191557640 is about 13840.4349642632. The cubic root of 191557640 is about 576.4564363742.

The spelling of 191557640 in words is "one hundred ninety-one million, five hundred fifty-seven thousand, six hundred forty".