20320621 has 4 divisors (see below), whose sum is σ = 20340700. Its totient is φ = 20300544.

The previous prime is 20320609. The next prime is 20320669. The reversal of 20320621 is 12602302.

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 13586596 + 6734025 = 3686^2 + 2595^2 .

It is a cyclic number.

It is not a de Polignac number, because 20320621 - 2¹³ = 20312429 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20320595 and 20320604.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20320021) 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, 8436 + ... + 10573.

It is an arithmetic number, because the mean of its divisors is an integer number (5085175).

Almost surely, 2^20320621 is an apocalyptic number.

It is an amenable number.

20320621 is a deficient number, since it is larger than the sum of its proper divisors (20079).

20320621 is a wasteful number, since it uses less digits than its factorization.

20320621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20078.

The product of its (nonzero) digits is 144, while the sum is 16.

The square root of 20320621 is about 4507.8399483566. The cubic root of 20320621 is about 272.8845777732.

Adding to 20320621 its reverse (12602302), we get a palindrome (32922923).

The spelling of 20320621 in words is "twenty million, three hundred twenty thousand, six hundred twenty-one".