261738691 has 4 divisors (see below), whose sum is σ = 266175000. Its totient is φ = 257302384.

The previous prime is 261738671. The next prime is 261738707. The reversal of 261738691 is 196837162.

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 261738691 - 2⁹ = 261738179 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (261738641) 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, 2218066 + ... + 2218183.

It is an arithmetic number, because the mean of its divisors is an integer number (66543750).

Almost surely, 2^261738691 is an apocalyptic number.

261738691 is a deficient number, since it is larger than the sum of its proper divisors (4436309).

261738691 is an equidigital number, since it uses as much as digits as its factorization.

261738691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4436308.

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

The square root of 261738691 is about 16178.3401806242. The cubic root of 261738691 is about 639.6699885526.

The spelling of 261738691 in words is "two hundred sixty-one million, seven hundred thirty-eight thousand, six hundred ninety-one".