261997427 has 2 divisors, whose sum is σ = 261997428. Its totient is φ = 261997426.

The previous prime is 261997363. The next prime is 261997429. The reversal of 261997427 is 724799162.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 261997427 - 2⁶ = 261997363 is a prime.

Together with 261997429, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (261997429) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130998713 + 130998714.

It is an arithmetic number, because the mean of its divisors is an integer number (130998714).

Almost surely, 2^261997427 is an apocalyptic number.

261997427 is a deficient number, since it is larger than the sum of its proper divisors (1).

261997427 is an equidigital number, since it uses as much as digits as its factorization.

261997427 is an evil number, because the sum of its binary digits is even.

The product of its digits is 381024, while the sum is 47.

The square root of 261997427 is about 16186.3345758081. The cubic root of 261997427 is about 639.8806963490.

The spelling of 261997427 in words is "two hundred sixty-one million, nine hundred ninety-seven thousand, four hundred twenty-seven".