261951911 has 12 divisors (see below), whose sum is σ = 289174536. Its totient is φ = 235884480.

The previous prime is 261951863. The next prime is 261951919. The reversal of 261951911 is 119159162.

It is not a de Polignac number, because 261951911 - 2¹⁸ = 261689767 is a prime.

It is a hoax number, since the sum of its digits (35) coincides with the sum of the digits of its distinct prime factors.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261951919) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 15860 + ... + 27846.

It is an arithmetic number, because the mean of its divisors is an integer number (24097878).

Almost surely, 2^261951911 is an apocalyptic number.

261951911 is a deficient number, since it is larger than the sum of its proper divisors (27222625).

261951911 is a wasteful number, since it uses less digits than its factorization.

261951911 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12082 (or 12041 counting only the distinct ones).

The product of its digits is 4860, while the sum is 35.

The square root of 261951911 is about 16184.9285138984. The cubic root of 261951911 is about 639.8436393737.

The spelling of 261951911 in words is "two hundred sixty-one million, nine hundred fifty-one thousand, nine hundred eleven".