261673891 has 4 divisors (see below), whose sum is σ = 261733032. Its totient is φ = 261614752.

The previous prime is 261673889. The next prime is 261673897. The reversal of 261673891 is 198376162.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 261673891 - 2¹ = 261673889 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (261673897) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 22345 + ... + 31978.

It is an arithmetic number, because the mean of its divisors is an integer number (65433258).

Almost surely, 2^261673891 is an apocalyptic number.

261673891 is a deficient number, since it is larger than the sum of its proper divisors (59141).

261673891 is an equidigital number, since it uses as much as digits as its factorization.

261673891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 59140.

The product of its digits is 108864, while the sum is 43.

The square root of 261673891 is about 16176.3373790237. The cubic root of 261673891 is about 639.6171953943.

The spelling of 261673891 in words is "two hundred sixty-one million, six hundred seventy-three thousand, eight hundred ninety-one".