26991 has 6 divisors (see below), whose sum is σ = 39000. Its totient is φ = 17988.

The previous prime is 26987. The next prime is 26993. The reversal of 26991 is 19962.

It is a happy number.

It is not a de Polignac number, because 26991 - 2² = 26987 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (26993) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1491 + ... + 1508.

It is an arithmetic number, because the mean of its divisors is an integer number (6500).

2²⁶⁹⁹¹ is an apocalyptic number.

26991 is a deficient number, since it is larger than the sum of its proper divisors (12009).

26991 is a wasteful number, since it uses less digits than its factorization.

26991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3005 (or 3002 counting only the distinct ones).

The product of its digits is 972, while the sum is 27.

The square root of 26991 is about 164.2893788411. The cubic root of 26991 is about 29.9966662962.

The spelling of 26991 in words is "twenty-six thousand, nine hundred ninety-one".