261999 has 12 divisors (see below), whose sum is σ = 387816. Its totient is φ = 170352.

The previous prime is 261983. The next prime is 262007. The reversal of 261999 is 999162.

261999 is digitally balanced in base 7, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 261999 - 2⁴ = 261983 is a prime.

261999 is a modest number, since divided by 999 gives 261 as remainder.

261999 is strictly pandigital in base 7.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261959) 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, 49 + ... + 725.

It is an arithmetic number, because the mean of its divisors is an integer number (32318).

2²⁶¹⁹⁹⁹ is an apocalyptic number.

261999 is a deficient number, since it is larger than the sum of its proper divisors (125817).

261999 is a wasteful number, since it uses less digits than its factorization.

261999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 726 (or 723 counting only the distinct ones).

The product of its digits is 8748, while the sum is 36.

The square root of 261999 is about 511.8583788510. The cubic root of 261999 is about 63.9881976934.

It can be divided in two parts, 26 and 1999, that added together give a square (2025 = 45²).

The spelling of 261999 in words is "two hundred sixty-one thousand, nine hundred ninety-nine".