20881909 has 4 divisors (see below), whose sum is σ = 20935980. Its totient is φ = 20827840.

The previous prime is 20881901. The next prime is 20881919. The reversal of 20881909 is 90918802.

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 6517809 + 14364100 = 2553^2 + 3790^2 .

It is a cyclic number.

It is not a de Polignac number, because 20881909 - 2³ = 20881901 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20881901) 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, 26452 + ... + 27229.

It is an arithmetic number, because the mean of its divisors is an integer number (5233995).

Almost surely, 2^20881909 is an apocalyptic number.

It is an amenable number.

20881909 is a deficient number, since it is larger than the sum of its proper divisors (54071).

20881909 is an equidigital number, since it uses as much as digits as its factorization.

20881909 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 54070.

The product of its (nonzero) digits is 10368, while the sum is 37.

The square root of 20881909 is about 4569.6727453944. The cubic root of 20881909 is about 275.3742958335.

The spelling of 20881909 in words is "twenty million, eight hundred eighty-one thousand, nine hundred nine".