261501271 has 2 divisors, whose sum is σ = 261501272. Its totient is φ = 261501270.

The previous prime is 261501269. The next prime is 261501277. The reversal of 261501271 is 172105162.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 261501271 - 2¹ = 261501269 is a prime.

Together with 261501269, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261501277) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130750635 + 130750636.

It is an arithmetic number, because the mean of its divisors is an integer number (130750636).

Almost surely, 2^261501271 is an apocalyptic number.

261501271 is a deficient number, since it is larger than the sum of its proper divisors (1).

261501271 is an equidigital number, since it uses as much as digits as its factorization.

261501271 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 840, while the sum is 25.

The square root of 261501271 is about 16171.0009275864. Note that the first 3 decimals coincide. The cubic root of 261501271 is about 639.4765177399.

The spelling of 261501271 in words is "two hundred sixty-one million, five hundred one thousand, two hundred seventy-one".