20004990721 has 3 divisors (see below), whose sum is σ = 20005132161. Its totient is φ = 20004849282.

The previous prime is 20004990683. The next prime is 20004990757. The reversal of 20004990721 is 12709940002.

It is a happy number.

The square root of 20004990721 is 141439.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is not a de Polignac number, because 20004990721 - 2¹⁵ = 20004957953 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20004990781) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 70720 + ... + 212158.

It is an arithmetic number, because the mean of its divisors is an integer number (6668377387).

Almost surely, 2^20004990721 is an apocalyptic number.

20004990721 is the 141439-th square number.

20004990721 is the 70720-th centered octagonal number.

It is an amenable number.

20004990721 is a deficient number, since it is larger than the sum of its proper divisors (141440).

20004990721 is an frugal number, since it uses more digits than its factorization.

20004990721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 282878 (or 141439 counting only the distinct ones).

The product of its (nonzero) digits is 9072, while the sum is 34.

The spelling of 20004990721 in words is "twenty billion, four million, nine hundred ninety thousand, seven hundred twenty-one".