20990911 has 2 divisors, whose sum is σ = 20990912. Its totient is φ = 20990910.

The previous prime is 20990891. The next prime is 20990929. The reversal of 20990911 is 11909902.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20990911 - 2⁹ = 20990399 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20990111) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10495455 + 10495456.

It is an arithmetic number, because the mean of its divisors is an integer number (10495456).

Almost surely, 2^20990911 is an apocalyptic number.

20990911 is a deficient number, since it is larger than the sum of its proper divisors (1).

20990911 is an equidigital number, since it uses as much as digits as its factorization.

20990911 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1458, while the sum is 31.

The square root of 20990911 is about 4581.5838964271. The cubic root of 20990911 is about 275.8526089391.

The spelling of 20990911 in words is "twenty million, nine hundred ninety thousand, nine hundred eleven".