261551567 has 2 divisors, whose sum is σ = 261551568. Its totient is φ = 261551566.

The previous prime is 261551539. The next prime is 261551573. The reversal of 261551567 is 765155162.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 261551567 - 2¹⁰ = 261550543 is a prime.

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 261551567.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261551527) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130775783 + 130775784.

It is an arithmetic number, because the mean of its divisors is an integer number (130775784).

Almost surely, 2^261551567 is an apocalyptic number.

261551567 is a deficient number, since it is larger than the sum of its proper divisors (1).

261551567 is an equidigital number, since it uses as much as digits as its factorization.

261551567 is an evil number, because the sum of its binary digits is even.

The product of its digits is 63000, while the sum is 38.

The square root of 261551567 is about 16172.5559822806. Note that the first 3 decimals coincide. The cubic root of 261551567 is about 639.5175131418.

The spelling of 261551567 in words is "two hundred sixty-one million, five hundred fifty-one thousand, five hundred sixty-seven".