391258261 has 2 divisors, whose sum is σ = 391258262. Its totient is φ = 391258260.

The previous prime is 391258253. The next prime is 391258271. The reversal of 391258261 is 162852193.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 353816100 + 37442161 = 18810^2 + 6119^2 .

It is a cyclic number.

It is not a de Polignac number, because 391258261 - 2³ = 391258253 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 391258261.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (391258211) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 195629130 + 195629131.

It is an arithmetic number, because the mean of its divisors is an integer number (195629131).

Almost surely, 2^391258261 is an apocalyptic number.

It is an amenable number.

391258261 is a deficient number, since it is larger than the sum of its proper divisors (1).

391258261 is an equidigital number, since it uses as much as digits as its factorization.

391258261 is an evil number, because the sum of its binary digits is even.

The product of its digits is 25920, while the sum is 37.

The square root of 391258261 is about 19780.2492653657. The cubic root of 391258261 is about 731.3992434468.

The spelling of 391258261 in words is "three hundred ninety-one million, two hundred fifty-eight thousand, two hundred sixty-one".