20205357621 has 4 divisors (see below), whose sum is σ = 26940476832. Its totient is φ = 13470238412.

The previous prime is 20205357619. The next prime is 20205357629. The reversal of 20205357621 is 12675350202.

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 20205357621 - 2¹ = 20205357619 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20205357629) 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, 3367559601 + ... + 3367559606.

It is an arithmetic number, because the mean of its divisors is an integer number (6735119208).

Almost surely, 2^20205357621 is an apocalyptic number.

It is an amenable number.

20205357621 is a deficient number, since it is larger than the sum of its proper divisors (6735119211).

20205357621 is an equidigital number, since it uses as much as digits as its factorization.

20205357621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6735119210.

The product of its (nonzero) digits is 25200, while the sum is 33.

The spelling of 20205357621 in words is "twenty billion, two hundred five million, three hundred fifty-seven thousand, six hundred twenty-one".