191991042 has 12 divisors (see below), whose sum is σ = 415980630. Its totient is φ = 63997008.

The previous prime is 191990999. The next prime is 191991043. The reversal of 191991042 is 240199191.

It can be written as a sum of positive squares in only one way, i.e., 175271121 + 16719921 = 13239^2 + 4089^2 .

It is a junction number, because it is equal to n+sod(n) for n = 191990988 and 191991006.

It is not an unprimeable number, because it can be changed into a prime (191991043) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 5333067 + ... + 5333102.

Almost surely, 2^191991042 is an apocalyptic number.

191991042 is an abundant number, since it is smaller than the sum of its proper divisors (223989588).

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

191991042 is a wasteful number, since it uses less digits than its factorization.

191991042 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10666177 (or 10666174 counting only the distinct ones).

The product of its (nonzero) digits is 5832, while the sum is 36.

The square root of 191991042 is about 13856.0832127986. The cubic root of 191991042 is about 576.8908559892.

The spelling of 191991042 in words is "one hundred ninety-one million, nine hundred ninety-one thousand, forty-two".