20160221521 has 6 divisors (see below), whose sum is σ = 22159582466. Its totient is φ = 18327474000.

The previous prime is 20160221513. The next prime is 20160221531. The reversal of 20160221521 is 12512206102.

It can be written as a sum of positive squares in only one way, i.e., 20135610000 + 24611521 = 141900^2 + 4961^2 .

It is not a de Polignac number, because 20160221521 - 2³ = 20160221513 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20160221492 and 20160221501.

It is not an unprimeable number, because it can be changed into a prime (20160221531) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 83306580 + ... + 83306821.

Almost surely, 2^20160221521 is an apocalyptic number.

It is an amenable number.

20160221521 is a deficient number, since it is larger than the sum of its proper divisors (1999360945).

20160221521 is a wasteful number, since it uses less digits than its factorization.

20160221521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 166613423 (or 166613412 counting only the distinct ones).

The product of its (nonzero) digits is 480, while the sum is 22.

Adding to 20160221521 its reverse (12512206102), we get a palindrome (32672427623).

The spelling of 20160221521 in words is "twenty billion, one hundred sixty million, two hundred twenty-one thousand, five hundred twenty-one".