261572539 has 2 divisors, whose sum is σ = 261572540. Its totient is φ = 261572538.

The previous prime is 261572501. The next prime is 261572561. The reversal of 261572539 is 935275162.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 261572539 - 2¹⁵ = 261539771 is a prime.

It is not a weakly prime, because it can be changed into another prime (261572039) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130786269 + 130786270.

It is an arithmetic number, because the mean of its divisors is an integer number (130786270).

Almost surely, 2^261572539 is an apocalyptic number.

261572539 is a deficient number, since it is larger than the sum of its proper divisors (1).

261572539 is an equidigital number, since it uses as much as digits as its factorization.

261572539 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 113400, while the sum is 40.

The square root of 261572539 is about 16173.2043516429. The cubic root of 261572539 is about 639.5346055046.

The spelling of 261572539 in words is "two hundred sixty-one million, five hundred seventy-two thousand, five hundred thirty-nine".