20990863 has 2 divisors, whose sum is σ = 20990864. Its totient is φ = 20990862.

The previous prime is 20990861. The next prime is 20990891. The reversal of 20990863 is 36809902.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20990863 - 2¹ = 20990861 is a prime.

It is a super-3 number, since 3×20990863³ (a number of 23 digits) contains 333 as substring.

Together with 20990861, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20990861) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10495431 + 10495432.

It is an arithmetic number, because the mean of its divisors is an integer number (10495432).

Almost surely, 2^20990863 is an apocalyptic number.

20990863 is a deficient number, since it is larger than the sum of its proper divisors (1).

20990863 is an equidigital number, since it uses as much as digits as its factorization.

20990863 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 23328, while the sum is 37.

The square root of 20990863 is about 4581.5786580610. The cubic root of 20990863 is about 275.8523986745.

The spelling of 20990863 in words is "twenty million, nine hundred ninety thousand, eight hundred sixty-three".