261759721 has 2 divisors, whose sum is σ = 261759722. Its totient is φ = 261759720.

The previous prime is 261759683. The next prime is 261759733. The reversal of 261759721 is 127957162.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 229098496 + 32661225 = 15136^2 + 5715^2 .

It is a cyclic number.

It is not a de Polignac number, because 261759721 - 2⁷ = 261759593 is a prime.

It is not a weakly prime, because it can be changed into another prime (261759221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130879860 + 130879861.

It is an arithmetic number, because the mean of its divisors is an integer number (130879861).

Almost surely, 2^261759721 is an apocalyptic number.

It is an amenable number.

261759721 is a deficient number, since it is larger than the sum of its proper divisors (1).

261759721 is an equidigital number, since it uses as much as digits as its factorization.

261759721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 52920, while the sum is 40.

The square root of 261759721 is about 16178.9901106342. The cubic root of 261759721 is about 639.6871200149.

The spelling of 261759721 in words is "two hundred sixty-one million, seven hundred fifty-nine thousand, seven hundred twenty-one".