261645379 has 2 divisors, whose sum is σ = 261645380. Its totient is φ = 261645378.

The previous prime is 261645347. The next prime is 261645403. The reversal of 261645379 is 973546162.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 261645379 - 2⁵ = 261645347 is a prime.

It is a nialpdrome in base 16.

It is not a weakly prime, because it can be changed into another prime (261645179) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130822689 + 130822690.

It is an arithmetic number, because the mean of its divisors is an integer number (130822690).

Almost surely, 2^261645379 is an apocalyptic number.

261645379 is a deficient number, since it is larger than the sum of its proper divisors (1).

261645379 is an equidigital number, since it uses as much as digits as its factorization.

261645379 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 272160, while the sum is 43.

The square root of 261645379 is about 16175.4560677590. The cubic root of 261645379 is about 639.5939636435.

The spelling of 261645379 in words is "two hundred sixty-one million, six hundred forty-five thousand, three hundred seventy-nine".