840257261 has 2 divisors, whose sum is σ = 840257262. Its totient is φ = 840257260.

The previous prime is 840257233. The next prime is 840257287. The reversal of 840257261 is 162752048.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 467381161 + 372876100 = 21619^2 + 19310^2 .

It is a cyclic number.

It is not a de Polignac number, because 840257261 - 2²² = 836062957 is a prime.

It is a Chen prime.

It is equal to p_43107884 and since 840257261 and 43107884 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (840257461) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 420128630 + 420128631.

It is an arithmetic number, because the mean of its divisors is an integer number (420128631).

Almost surely, 2^840257261 is an apocalyptic number.

It is an amenable number.

840257261 is a deficient number, since it is larger than the sum of its proper divisors (1).

840257261 is an equidigital number, since it uses as much as digits as its factorization.

840257261 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 26880, while the sum is 35.

The square root of 840257261 is about 28987.1913265152. The cubic root of 840257261 is about 943.6351099356.

The spelling of 840257261 in words is "eight hundred forty million, two hundred fifty-seven thousand, two hundred sixty-one".