20321689 has 4 divisors (see below), whose sum is σ = 20410660. Its totient is φ = 20232720.

The previous prime is 20321687. The next prime is 20321711. The reversal of 20321689 is 98612302.

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

It can be written as a sum of positive squares in 2 ways, for example, as 12369289 + 7952400 = 3517^2 + 2820^2 .

It is a cyclic number.

It is not a de Polignac number, because 20321689 - 2¹ = 20321687 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20321689.

It is not an unprimeable number, because it can be changed into a prime (20321687) 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, 44142 + ... + 44599.

It is an arithmetic number, because the mean of its divisors is an integer number (5102665).

Almost surely, 2^20321689 is an apocalyptic number.

It is an amenable number.

20321689 is a deficient number, since it is larger than the sum of its proper divisors (88971).

20321689 is an equidigital number, since it uses as much as digits as its factorization.

20321689 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 88970.

The product of its (nonzero) digits is 5184, while the sum is 31.

The square root of 20321689 is about 4507.9584070841. The cubic root of 20321689 is about 272.8893583952.

It can be divided in two parts, 2032 and 1689, that added together give a square (3721 = 61²).

The spelling of 20321689 in words is "twenty million, three hundred twenty-one thousand, six hundred eighty-nine".