261399057971 has 2 divisors, whose sum is σ = 261399057972. Its totient is φ = 261399057970.

The previous prime is 261399057943. The next prime is 261399057991. The reversal of 261399057971 is 179750993162.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-261399057971 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 261399057971.

It is not a weakly prime, because it can be changed into another prime (261399057991) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130699528985 + 130699528986.

It is an arithmetic number, because the mean of its divisors is an integer number (130699528986).

Almost surely, 2^261399057971 is an apocalyptic number.

261399057971 is a deficient number, since it is larger than the sum of its proper divisors (1).

261399057971 is an equidigital number, since it uses as much as digits as its factorization.

261399057971 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6429780, while the sum is 59.

The spelling of 261399057971 in words is "two hundred sixty-one billion, three hundred ninety-nine million, fifty-seven thousand, nine hundred seventy-one".