291611261 has 2 divisors, whose sum is σ = 291611262. Its totient is φ = 291611260.

The previous prime is 291611249. The next prime is 291611279. The reversal of 291611261 is 162116192.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 226502500 + 65108761 = 15050^2 + 8069^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-291611261 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (291611291) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 145805630 + 145805631.

It is an arithmetic number, because the mean of its divisors is an integer number (145805631).

Almost surely, 2^291611261 is an apocalyptic number.

It is an amenable number.

291611261 is a deficient number, since it is larger than the sum of its proper divisors (1).

291611261 is an equidigital number, since it uses as much as digits as its factorization.

291611261 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1296, while the sum is 29.

The square root of 291611261 is about 17076.6290877327. The cubic root of 291611261 is about 663.1342058344.

The spelling of 291611261 in words is "two hundred ninety-one million, six hundred eleven thousand, two hundred sixty-one".