261904691 has 2 divisors, whose sum is σ = 261904692. Its totient is φ = 261904690.

The previous prime is 261904673. The next prime is 261904693. The reversal of 261904691 is 196409162.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 261904691 - 2¹⁰ = 261903667 is a prime.

Together with 261904693, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (261904693) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130952345 + 130952346.

It is an arithmetic number, because the mean of its divisors is an integer number (130952346).

Almost surely, 2^261904691 is an apocalyptic number.

261904691 is a deficient number, since it is larger than the sum of its proper divisors (1).

261904691 is an equidigital number, since it uses as much as digits as its factorization.

261904691 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 23328, while the sum is 38.

The square root of 261904691 is about 16183.4696836000. The cubic root of 261904691 is about 639.8051905453.

The spelling of 261904691 in words is "two hundred sixty-one million, nine hundred four thousand, six hundred ninety-one".