261694391 has 16 divisors (see below), whose sum is σ = 328512000. Its totient is φ = 203262048.

The previous prime is 261694387. The next prime is 261694399. The reversal of 261694391 is 193496162.

It is a cyclic number.

It is not a de Polignac number, because 261694391 - 2² = 261694387 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261694399) 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 15 ways as a sum of consecutive naturals, for example, 39716 + ... + 45833.

It is an arithmetic number, because the mean of its divisors is an integer number (20532000).

Almost surely, 2^261694391 is an apocalyptic number.

261694391 is a deficient number, since it is larger than the sum of its proper divisors (66817609).

261694391 is a wasteful number, since it uses less digits than its factorization.

261694391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 85598.

The product of its digits is 69984, while the sum is 41.

The square root of 261694391 is about 16176.9710081956. The cubic root of 261694391 is about 639.6338978760.

The spelling of 261694391 in words is "two hundred sixty-one million, six hundred ninety-four thousand, three hundred ninety-one".