261020581 has 2 divisors, whose sum is σ = 261020582. Its totient is φ = 261020580.

The previous prime is 261020569. The next prime is 261020587. The reversal of 261020581 is 185020162.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 152152225 + 108868356 = 12335^2 + 10434^2 .

It is a cyclic number.

It is not a de Polignac number, because 261020581 - 2⁵ = 261020549 is a prime.

It is a super-2 number, since 2×261020581² = 136263487411155122, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261020587) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130510290 + 130510291.

It is an arithmetic number, because the mean of its divisors is an integer number (130510291).

Almost surely, 2^261020581 is an apocalyptic number.

It is an amenable number.

261020581 is a deficient number, since it is larger than the sum of its proper divisors (1).

261020581 is an equidigital number, since it uses as much as digits as its factorization.

261020581 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 960, while the sum is 25.

The square root of 261020581 is about 16156.1313748063. The cubic root of 261020581 is about 639.0844501652.

The spelling of 261020581 in words is "two hundred sixty-one million, twenty thousand, five hundred eighty-one".