20940989 has 4 divisors (see below), whose sum is σ = 21336156. Its totient is φ = 20545824.

The previous prime is 20940979. The next prime is 20941007. The reversal of 20940989 is 98904902.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 18852964 + 2088025 = 4342^2 + 1445^2 .

It is a cyclic number.

It is not a de Polignac number, because 20940989 - 2¹² = 20936893 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20940979) 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, 197504 + ... + 197609.

It is an arithmetic number, because the mean of its divisors is an integer number (5334039).

Almost surely, 2^20940989 is an apocalyptic number.

It is an amenable number.

20940989 is a deficient number, since it is larger than the sum of its proper divisors (395167).

20940989 is an equidigital number, since it uses as much as digits as its factorization.

20940989 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 395166.

The product of its (nonzero) digits is 46656, while the sum is 41.

The square root of 20940989 is about 4576.1325374163. The cubic root of 20940989 is about 275.6337515882.

The spelling of 20940989 in words is "twenty million, nine hundred forty thousand, nine hundred eighty-nine".