20210205621 has 4 divisors (see below), whose sum is σ = 26946940832. Its totient is φ = 13473470412.

The previous prime is 20210205607. The next prime is 20210205637. The reversal of 20210205621 is 12650201202.

It is a happy number.

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 not a de Polignac number, because 20210205621 - 2³⁴ = 3030336437 is a prime.

It is a super-2 number, since 2×20210205621² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20210203621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3368367601 + ... + 3368367606.

It is an arithmetic number, because the mean of its divisors is an integer number (6736735208).

Almost surely, 2^20210205621 is an apocalyptic number.

It is an amenable number.

20210205621 is a deficient number, since it is larger than the sum of its proper divisors (6736735211).

20210205621 is an equidigital number, since it uses as much as digits as its factorization.

20210205621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6736735210.

The product of its (nonzero) digits is 480, while the sum is 21.

Adding to 20210205621 its reverse (12650201202), we get a palindrome (32860406823).

The spelling of 20210205621 in words is "twenty billion, two hundred ten million, two hundred five thousand, six hundred twenty-one".