20989613 has 2 divisors, whose sum is σ = 20989614. Its totient is φ = 20989612.

The previous prime is 20989609. The next prime is 20989627. The reversal of 20989613 is 31698902.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20912329 + 77284 = 4573^2 + 278^2 .

It is a cyclic number.

It is not a de Polignac number, because 20989613 - 2² = 20989609 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20989603) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10494806 + 10494807.

It is an arithmetic number, because the mean of its divisors is an integer number (10494807).

Almost surely, 2^20989613 is an apocalyptic number.

It is an amenable number.

20989613 is a deficient number, since it is larger than the sum of its proper divisors (1).

20989613 is an equidigital number, since it uses as much as digits as its factorization.

20989613 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 23328, while the sum is 38.

The square root of 20989613 is about 4581.4422401685. The cubic root of 20989613 is about 275.8469229215.

It can be divided in two parts, 2098 and 9613, that added together give a palindrome (11711).

The spelling of 20989613 in words is "twenty million, nine hundred eighty-nine thousand, six hundred thirteen".