261670397 has 2 divisors, whose sum is σ = 261670398. Its totient is φ = 261670396.

The previous prime is 261670303. The next prime is 261670399. The reversal of 261670397 is 793076162.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 253796761 + 7873636 = 15931^2 + 2806^2 .

It is a cyclic number.

It is not a de Polignac number, because 261670397 - 2¹⁸ = 261408253 is a prime.

It is a super-2 number, since 2×261670397² = 136942793332275218, which contains 22 as substring.

Together with 261670399, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261670399) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130835198 + 130835199.

It is an arithmetic number, because the mean of its divisors is an integer number (130835199).

Almost surely, 2^261670397 is an apocalyptic number.

It is an amenable number.

261670397 is a deficient number, since it is larger than the sum of its proper divisors (1).

261670397 is an equidigital number, since it uses as much as digits as its factorization.

261670397 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 95256, while the sum is 41.

The square root of 261670397 is about 16176.2293814102. The cubic root of 261670397 is about 639.6143485526.

The spelling of 261670397 in words is "two hundred sixty-one million, six hundred seventy thousand, three hundred ninety-seven".