261989 has 8 divisors (see below), whose sum is σ = 322560. Its totient is φ = 207216.

The previous prime is 261983. The next prime is 262007. The reversal of 261989 is 989162.

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 261989 - 2⁴ = 261973 is a prime.

It is a super-2 number, since 2×261989² = 137276472242, which contains 22 as substring.

It is a congruent number.

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 7 ways as a sum of consecutive naturals, for example, 1349 + ... + 1530.

It is an arithmetic number, because the mean of its divisors is an integer number (40320).

2²⁶¹⁹⁸⁹ is an apocalyptic number.

It is an amenable number.

261989 is a deficient number, since it is larger than the sum of its proper divisors (60571).

261989 is a wasteful number, since it uses less digits than its factorization.

261989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2899.

The product of its digits is 7776, while the sum is 35.

The square root of 261989 is about 511.8486104309. The cubic root of 261989 is about 63.9873835808.

The spelling of 261989 in words is "two hundred sixty-one thousand, nine hundred eighty-nine".