261904997 has 2 divisors, whose sum is σ = 261904998. Its totient is φ = 261904996.

The previous prime is 261904961. The next prime is 261905011. The reversal of 261904997 is 799409162.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 215678596 + 46226401 = 14686^2 + 6799^2 .

It is a cyclic number.

It is not a de Polignac number, because 261904997 - 2¹⁰ = 261903973 is a prime.

It is a super-3 number, since 3×261904997³ (a number of 26 digits) contains 333 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261904927) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130952498 + 130952499.

It is an arithmetic number, because the mean of its divisors is an integer number (130952499).

Almost surely, 2^261904997 is an apocalyptic number.

It is an amenable number.

261904997 is a deficient number, since it is larger than the sum of its proper divisors (1).

261904997 is an equidigital number, since it uses as much as digits as its factorization.

261904997 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 244944, while the sum is 47.

The square root of 261904997 is about 16183.4791376885. The cubic root of 261904997 is about 639.8054397203.

The spelling of 261904997 in words is "two hundred sixty-one million, nine hundred four thousand, nine hundred ninety-seven".