261515897 has 2 divisors, whose sum is σ = 261515898. Its totient is φ = 261515896.

The previous prime is 261515893. The next prime is 261515921. The reversal of 261515897 is 798515162.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 260467321 + 1048576 = 16139^2 + 1024^2 .

It is a cyclic number.

It is not a de Polignac number, because 261515897 - 2² = 261515893 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (261515893) 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, 130757948 + 130757949.

It is an arithmetic number, because the mean of its divisors is an integer number (130757949).

Almost surely, 2^261515897 is an apocalyptic number.

It is an amenable number.

261515897 is a deficient number, since it is larger than the sum of its proper divisors (1).

261515897 is an equidigital number, since it uses as much as digits as its factorization.

261515897 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 151200, while the sum is 44.

The square root of 261515897 is about 16171.4531505366. The cubic root of 261515897 is about 639.4884396822.

The spelling of 261515897 in words is "two hundred sixty-one million, five hundred fifteen thousand, eight hundred ninety-seven".