21695 has 4 divisors (see below), whose sum is σ = 26040. Its totient is φ = 17352.

The previous prime is 21683. The next prime is 21701. The reversal of 21695 is 59612.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21695 - 2¹² = 17599 is a prime.

It is a nialpdrome in base 15.

It is a self number, because there is not a number n which added to its sum of digits gives 21695.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2165 + ... + 2174.

It is an arithmetic number, because the mean of its divisors is an integer number (6510).

2²¹⁶⁹⁵ is an apocalyptic number.

21695 is a deficient number, since it is larger than the sum of its proper divisors (4345).

21695 is an equidigital number, since it uses as much as digits as its factorization.

21695 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4344.

The product of its digits is 540, while the sum is 23.

The square root of 21695 is about 147.2922265430. The cubic root of 21695 is about 27.8903020811.

The spelling of 21695 in words is "twenty-one thousand, six hundred ninety-five".