20231621 has 4 divisors (see below), whose sum is σ = 20258700. Its totient is φ = 20204544.

The previous prime is 20231597. The next prime is 20231639. The reversal of 20231621 is 12613202.

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 4351396 + 15880225 = 2086^2 + 3985^2 .

It is a cyclic number.

It is not a de Polignac number, because 20231621 - 2⁶ = 20231557 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 20231621.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20231641) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12386 + ... + 13923.

It is an arithmetic number, because the mean of its divisors is an integer number (5064675).

Almost surely, 2^20231621 is an apocalyptic number.

It is an amenable number.

20231621 is a deficient number, since it is larger than the sum of its proper divisors (27079).

20231621 is an equidigital number, since it uses as much as digits as its factorization.

20231621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27078.

The product of its (nonzero) digits is 144, while the sum is 17.

The square root of 20231621 is about 4497.9574253210. The cubic root of 20231621 is about 272.4856025836.

Adding to 20231621 its reverse (12613202), we get a palindrome (32844823).

The spelling of 20231621 in words is "twenty million, two hundred thirty-one thousand, six hundred twenty-one".