261949657 has 2 divisors, whose sum is σ = 261949658. Its totient is φ = 261949656.

The previous prime is 261949643. The next prime is 261949669. The reversal of 261949657 is 756949162.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 214944921 + 47004736 = 14661^2 + 6856^2 .

It is a cyclic number.

It is not a de Polignac number, because 261949657 - 2¹⁹ = 261425369 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 261949657.

It is not a weakly prime, because it can be changed into another prime (261949607) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130974828 + 130974829.

It is an arithmetic number, because the mean of its divisors is an integer number (130974829).

Almost surely, 2^261949657 is an apocalyptic number.

It is an amenable number.

261949657 is a deficient number, since it is larger than the sum of its proper divisors (1).

261949657 is an equidigital number, since it uses as much as digits as its factorization.

261949657 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 816480, while the sum is 49.

The square root of 261949657 is about 16184.8588810654. The cubic root of 261949657 is about 639.8418041619.

The spelling of 261949657 in words is "two hundred sixty-one million, nine hundred forty-nine thousand, six hundred fifty-seven".