261949791 has 4 divisors (see below), whose sum is σ = 349266392. Its totient is φ = 174633192.

The previous prime is 261949757. The next prime is 261949801. The reversal of 261949791 is 197949162.

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

It is not a de Polignac number, because 261949791 - 2¹¹ = 261947743 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 261949791.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261949711) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 43658296 + ... + 43658301.

It is an arithmetic number, because the mean of its divisors is an integer number (87316598).

Almost surely, 2^261949791 is an apocalyptic number.

261949791 is a deficient number, since it is larger than the sum of its proper divisors (87316601).

261949791 is an equidigital number, since it uses as much as digits as its factorization.

261949791 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 87316600.

The product of its digits is 244944, while the sum is 48.

The square root of 261949791 is about 16184.8630207364. The cubic root of 261949791 is about 639.8419132653.

The spelling of 261949791 in words is "two hundred sixty-one million, nine hundred forty-nine thousand, seven hundred ninety-one".