20699 has 4 divisors (see below), whose sum is σ = 23664. Its totient is φ = 17736.

The previous prime is 20693. The next prime is 20707. The reversal of 20699 is 99602.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 99602 = 2 ⋅49801.

It is a cyclic number.

It is not a de Polignac number, because 20699 - 2⁸ = 20443 is a prime.

It is a Duffinian number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 20699.

It is not an unprimeable number, because it can be changed into a prime (20693) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1472 + ... + 1485.

It is an arithmetic number, because the mean of its divisors is an integer number (5916).

2²⁰⁶⁹⁹ is an apocalyptic number.

20699 is a deficient number, since it is larger than the sum of its proper divisors (2965).

20699 is an equidigital number, since it uses as much as digits as its factorization.

20699 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2964.

The product of its (nonzero) digits is 972, while the sum is 26.

The square root of 20699 is about 143.8714704172. The cubic root of 20699 is about 27.4567916502.

The spelling of 20699 in words is "twenty thousand, six hundred ninety-nine".