20021663 has 2 divisors, whose sum is σ = 20021664. Its totient is φ = 20021662.

The previous prime is 20021641. The next prime is 20021669. The reversal of 20021663 is 36612002.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20021663 - 2²⁴ = 3244447 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20021669) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10010831 + 10010832.

It is an arithmetic number, because the mean of its divisors is an integer number (10010832).

Almost surely, 2^20021663 is an apocalyptic number.

20021663 is a deficient number, since it is larger than the sum of its proper divisors (1).

20021663 is an equidigital number, since it uses as much as digits as its factorization.

20021663 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 432, while the sum is 20.

The square root of 20021663 is about 4474.5572965378. The cubic root of 20021663 is about 271.5397303445.

Adding to 20021663 its reverse (36612002), we get a palindrome (56633665).

The spelling of 20021663 in words is "twenty million, twenty-one thousand, six hundred sixty-three".