20389621 has 4 divisors (see below), whose sum is σ = 23302432. Its totient is φ = 17476812.

The previous prime is 20389619. The next prime is 20389631. The reversal of 20389621 is 12698302.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 20389621 - 2¹ = 20389619 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20389631) 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, 1456395 + ... + 1456408.

It is an arithmetic number, because the mean of its divisors is an integer number (5825608).

Almost surely, 2^20389621 is an apocalyptic number.

It is an amenable number.

20389621 is a deficient number, since it is larger than the sum of its proper divisors (2912811).

20389621 is an equidigital number, since it uses as much as digits as its factorization.

20389621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2912810.

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

The square root of 20389621 is about 4515.4867954629. The cubic root of 20389621 is about 273.1930946609.

The spelling of 20389621 in words is "twenty million, three hundred eighty-nine thousand, six hundred twenty-one".