261279391 has 8 divisors (see below), whose sum is σ = 263941920. Its totient is φ = 258623232.

The previous prime is 261279373. The next prime is 261279407. The reversal of 261279391 is 193972162.

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 261279391 - 2¹⁷ = 261148319 is a prime.

It is a super-2 number, since 2×261279391² = 136533840322661762, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261279301) 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, 148171 + ... + 149923.

It is an arithmetic number, because the mean of its divisors is an integer number (32992740).

Almost surely, 2^261279391 is an apocalyptic number.

261279391 is a deficient number, since it is larger than the sum of its proper divisors (2662529).

261279391 is a wasteful number, since it uses less digits than its factorization.

261279391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3185.

The product of its digits is 40824, while the sum is 40.

The square root of 261279391 is about 16164.1390429556. The cubic root of 261279391 is about 639.2956044084.

The spelling of 261279391 in words is "two hundred sixty-one million, two hundred seventy-nine thousand, three hundred ninety-one".