191273290261 has 4 divisors (see below), whose sum is σ = 191296429900. Its totient is φ = 191250150624.

The previous prime is 191273290237. The next prime is 191273290267. The reversal of 191273290261 is 162092372191.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 152810628100 + 38462662161 = 390910^2 + 196119^2 .

It is a cyclic number.

It is not a de Polignac number, because 191273290261 - 2¹⁹ = 191272765973 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (191273290267) 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, 11557416 + ... + 11573953.

It is an arithmetic number, because the mean of its divisors is an integer number (47824107475).

Almost surely, 2^191273290261 is an apocalyptic number.

It is an amenable number.

191273290261 is a deficient number, since it is larger than the sum of its proper divisors (23139639).

191273290261 is an equidigital number, since it uses as much as digits as its factorization.

191273290261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23139638.

The product of its (nonzero) digits is 81648, while the sum is 43.

The spelling of 191273290261 in words is "one hundred ninety-one billion, two hundred seventy-three million, two hundred ninety thousand, two hundred sixty-one".