20905663 has 2 divisors, whose sum is σ = 20905664. Its totient is φ = 20905662.

The previous prime is 20905657. The next prime is 20905679. The reversal of 20905663 is 36650902.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20905663 - 2¹⁷ = 20774591 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20905603) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10452831 + 10452832.

It is an arithmetic number, because the mean of its divisors is an integer number (10452832).

Almost surely, 2^20905663 is an apocalyptic number.

20905663 is a deficient number, since it is larger than the sum of its proper divisors (1).

20905663 is an equidigital number, since it uses as much as digits as its factorization.

20905663 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 9720, while the sum is 31.

The square root of 20905663 is about 4572.2710986992. The cubic root of 20905663 is about 275.4786726617.

The spelling of 20905663 in words is "twenty million, nine hundred five thousand, six hundred sixty-three".