261791999 has 8 divisors (see below), whose sum is σ = 299316768. Its totient is φ = 224298720.

The previous prime is 261791953. The next prime is 261792001. The reversal of 261791999 is 999197162.

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

It is a cyclic number.

It is not a de Polignac number, because 261791999 - 2²⁰ = 260743423 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 261791999.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261791399) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 14009 + ... + 26829.

It is an arithmetic number, because the mean of its divisors is an integer number (37414596).

Almost surely, 2^261791999 is an apocalyptic number.

261791999 is a deficient number, since it is larger than the sum of its proper divisors (37524769).

261791999 is a wasteful number, since it uses less digits than its factorization.

261791999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15745.

The product of its digits is 551124, while the sum is 53.

The square root of 261791999 is about 16179.9876081535. The cubic root of 261791999 is about 639.7134125402.

The spelling of 261791999 in words is "two hundred sixty-one million, seven hundred ninety-one thousand, nine hundred ninety-nine".