261463639 has 2 divisors, whose sum is σ = 261463640. Its totient is φ = 261463638.

The previous prime is 261463613. The next prime is 261463661. The reversal of 261463639 is 936364162.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 261463639 - 2²¹ = 259366487 is a prime.

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, 130731819 + 130731820.

It is an arithmetic number, because the mean of its divisors is an integer number (130731820).

Almost surely, 2^261463639 is an apocalyptic number.

261463639 is a deficient number, since it is larger than the sum of its proper divisors (1).

261463639 is an equidigital number, since it uses as much as digits as its factorization.

261463639 is an evil number, because the sum of its binary digits is even.

The product of its digits is 139968, while the sum is 40.

The square root of 261463639 is about 16169.8373213833. The cubic root of 261463639 is about 639.4458411079.

The spelling of 261463639 in words is "two hundred sixty-one million, four hundred sixty-three thousand, six hundred thirty-nine".