261463661 has 2 divisors, whose sum is σ = 261463662. Its totient is φ = 261463660.

The previous prime is 261463639. The next prime is 261463669. The reversal of 261463661 is 166364162.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 219602761 + 41860900 = 14819^2 + 6470^2 .

It is a cyclic number.

It is not a de Polignac number, because 261463661 - 2¹⁸ = 261201517 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261463669) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130731830 + 130731831.

It is an arithmetic number, because the mean of its divisors is an integer number (130731831).

Almost surely, 2^261463661 is an apocalyptic number.

It is an amenable number.

261463661 is a deficient number, since it is larger than the sum of its proper divisors (1).

261463661 is an equidigital number, since it uses as much as digits as its factorization.

261463661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 31104, while the sum is 35.

The square root of 261463661 is about 16169.8380016622. The cubic root of 261463661 is about 639.4458590426.

The spelling of 261463661 in words is "two hundred sixty-one million, four hundred sixty-three thousand, six hundred sixty-one".