20806663 has 2 divisors, whose sum is σ = 20806664. Its totient is φ = 20806662.

The previous prime is 20806661. The next prime is 20806693. The reversal of 20806663 is 36660802.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20806663 - 2¹ = 20806661 is a prime.

Together with 20806661, 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 (20806661) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10403331 + 10403332.

It is an arithmetic number, because the mean of its divisors is an integer number (10403332).

Almost surely, 2^20806663 is an apocalyptic number.

20806663 is a deficient number, since it is larger than the sum of its proper divisors (1).

20806663 is an equidigital number, since it uses as much as digits as its factorization.

20806663 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 10368, while the sum is 31.

The square root of 20806663 is about 4561.4321216039. The cubic root of 20806663 is about 275.0431359332.

It can be divided in two parts, 20806 and 663, that multiplied together give a triangular number (13794378 = T₅₂₅₂).

The spelling of 20806663 in words is "twenty million, eight hundred six thousand, six hundred sixty-three".