20403221521 has 4 divisors (see below), whose sum is σ = 20425618944. Its totient is φ = 20380824100.

The previous prime is 20403221513. The next prime is 20403221537. The reversal of 20403221521 is 12512230402.

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 a cyclic number.

It is not a de Polignac number, because 20403221521 - 2³ = 20403221513 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20403221492 and 20403221501.

It is not an unprimeable number, because it can be changed into a prime (20403221021) 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, 11197345 + ... + 11199166.

It is an arithmetic number, because the mean of its divisors is an integer number (5106404736).

Almost surely, 2^20403221521 is an apocalyptic number.

It is an amenable number.

20403221521 is a deficient number, since it is larger than the sum of its proper divisors (22397423).

20403221521 is an equidigital number, since it uses as much as digits as its factorization.

20403221521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22397422.

The product of its (nonzero) digits is 960, while the sum is 22.

Adding to 20403221521 its reverse (12512230402), we get a palindrome (32915451923).

The spelling of 20403221521 in words is "twenty billion, four hundred three million, two hundred twenty-one thousand, five hundred twenty-one".