261671537 has 2 divisors, whose sum is σ = 261671538. Its totient is φ = 261671536.

The previous prime is 261671521. The next prime is 261671539. The reversal of 261671537 is 735176162.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 259886641 + 1784896 = 16121^2 + 1336^2 .

It is a cyclic number.

It is not a de Polignac number, because 261671537 - 2⁴ = 261671521 is a prime.

Together with 261671539, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 261671537.

It is not a weakly prime, because it can be changed into another prime (261671539) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130835768 + 130835769.

It is an arithmetic number, because the mean of its divisors is an integer number (130835769).

Almost surely, 2^261671537 is an apocalyptic number.

It is an amenable number.

261671537 is a deficient number, since it is larger than the sum of its proper divisors (1).

261671537 is an equidigital number, since it uses as much as digits as its factorization.

261671537 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 52920, while the sum is 38.

The square root of 261671537 is about 16176.2646182609. The cubic root of 261671537 is about 639.6152774047.

The spelling of 261671537 in words is "two hundred sixty-one million, six hundred seventy-one thousand, five hundred thirty-seven".