261664049 has 2 divisors, whose sum is σ = 261664050. Its totient is φ = 261664048.

The previous prime is 261664019. The next prime is 261664093. The reversal of 261664049 is 940466162.

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., 149621824 + 112042225 = 12232^2 + 10585^2 .

It is a cyclic number.

It is not a de Polignac number, because 261664049 - 2⁸ = 261663793 is a prime.

It is a super-3 number, since 3×261664049³ (a number of 26 digits) contains 333 as substring.

It is not a weakly prime, because it can be changed into another prime (261664019) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130832024 + 130832025.

It is an arithmetic number, because the mean of its divisors is an integer number (130832025).

Almost surely, 2^261664049 is an apocalyptic number.

It is an amenable number.

261664049 is a deficient number, since it is larger than the sum of its proper divisors (1).

261664049 is an equidigital number, since it uses as much as digits as its factorization.

261664049 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 62208, while the sum is 38.

The square root of 261664049 is about 16176.0331663854. The cubic root of 261664049 is about 639.6091762636.

The spelling of 261664049 in words is "two hundred sixty-one million, six hundred sixty-four thousand, forty-nine".