261402569 has 2 divisors, whose sum is σ = 261402570. Its totient is φ = 261402568.

The previous prime is 261402529. The next prime is 261402623. The reversal of 261402569 is 965204162.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 261242569 + 160000 = 16163^2 + 400^2 .

It is a cyclic number.

It is not a de Polignac number, because 261402569 - 2⁸ = 261402313 is a prime.

It is a super-2 number, since 2×261402569² = 136662606159599522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (261402529) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130701284 + 130701285.

It is an arithmetic number, because the mean of its divisors is an integer number (130701285).

Almost surely, 2^261402569 is an apocalyptic number.

It is an amenable number.

261402569 is a deficient number, since it is larger than the sum of its proper divisors (1).

261402569 is an equidigital number, since it uses as much as digits as its factorization.

261402569 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 25920, while the sum is 35.

The square root of 261402569 is about 16167.9488185731. The cubic root of 261402569 is about 639.3960521603.

The spelling of 261402569 in words is "two hundred sixty-one million, four hundred two thousand, five hundred sixty-nine".