20989998901 has 2 divisors, whose sum is σ = 20989998902. Its totient is φ = 20989998900.

The previous prime is 20989998859. The next prime is 20989998941. The reversal of 20989998901 is 10989998902.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19217167876 + 1772831025 = 138626^2 + 42105^2 .

It is a cyclic number.

It is not a de Polignac number, because 20989998901 - 2¹⁵ = 20989966133 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20989998941) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10494999450 + 10494999451.

It is an arithmetic number, because the mean of its divisors is an integer number (10494999451).

Almost surely, 2^20989998901 is an apocalyptic number.

It is an amenable number.

20989998901 is a deficient number, since it is larger than the sum of its proper divisors (1).

20989998901 is an equidigital number, since it uses as much as digits as its factorization.

20989998901 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 7558272, while the sum is 64.

Subtracting from 20989998901 its reverse (10989998902), we obtain a palindrome (9999999999).

The spelling of 20989998901 in words is "twenty billion, nine hundred eighty-nine million, nine hundred ninety-eight thousand, nine hundred one".