261987 has 16 divisors (see below), whose sum is σ = 404352. Its totient is φ = 149120.

The previous prime is 261983. The next prime is 262007. The reversal of 261987 is 789162.

It is a cyclic number.

It is not a de Polignac number, because 261987 - 2² = 261983 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a nialpdrome in base 8.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 261987.

It is not an unprimeable number, because it can be changed into a prime (261983) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 328 + ... + 794.

It is an arithmetic number, because the mean of its divisors is an integer number (25272).

261987 is a Friedman number, since it can be written as 8^6-79*2+1, using all its digits and the basic arithmetic operations.

2²⁶¹⁹⁸⁷ is an apocalyptic number.

261987 is a deficient number, since it is larger than the sum of its proper divisors (142365).

261987 is a wasteful number, since it uses less digits than its factorization.

261987 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 498.

The product of its digits is 6048, while the sum is 33.

The square root of 261987 is about 511.8466567245. The cubic root of 261987 is about 63.9872207558.

The spelling of 261987 in words is "two hundred sixty-one thousand, nine hundred eighty-seven".