261323391 has 8 divisors (see below), whose sum is σ = 398207104. Its totient is φ = 149327640.

The previous prime is 261323369. The next prime is 261323399. The reversal of 261323391 is 193323162.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 261323391 - 2⁹ = 261322879 is a prime.

It is the 16166-th Hogben number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261323399) by changing a digit.

It is a nontrivial repunit in base 16165.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6221965 + ... + 6222006.

It is an arithmetic number, because the mean of its divisors is an integer number (49775888).

Almost surely, 2^261323391 is an apocalyptic number.

261323391 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

261323391 is a deficient number, since it is larger than the sum of its proper divisors (136883713).

261323391 is a wasteful number, since it uses less digits than its factorization.

261323391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12443981.

The product of its digits is 5832, while the sum is 30.

The square root of 261323391 is about 16165.5000231976. The cubic root of 261323391 is about 639.3314886365.

The spelling of 261323391 in words is "two hundred sixty-one million, three hundred twenty-three thousand, three hundred ninety-one".