191291261 has 4 divisors (see below), whose sum is σ = 218618592. Its totient is φ = 163963932.

The previous prime is 191291237. The next prime is 191291267. The reversal of 191291261 is 162192191.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 162192191 = 7 ⋅23170313.

It is a cyclic number.

It is not a de Polignac number, because 191291261 - 2⁶ = 191291197 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (191291267) 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, 13663655 + ... + 13663668.

It is an arithmetic number, because the mean of its divisors is an integer number (54654648).

Almost surely, 2^191291261 is an apocalyptic number.

It is an amenable number.

191291261 is a deficient number, since it is larger than the sum of its proper divisors (27327331).

191291261 is an equidigital number, since it uses as much as digits as its factorization.

191291261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27327330.

The product of its digits is 1944, while the sum is 32.

The square root of 191291261 is about 13830.8084000900. The cubic root of 191291261 is about 576.1891067042.

The spelling of 191291261 in words is "one hundred ninety-one million, two hundred ninety-one thousand, two hundred sixty-one".