20508643 has 2 divisors, whose sum is σ = 20508644. Its totient is φ = 20508642.

The previous prime is 20508611. The next prime is 20508661. The reversal of 20508643 is 34680502.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20508643 - 2⁵ = 20508611 is a prime.

It is not a weakly prime, because it can be changed into another prime (20508043) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10254321 + 10254322.

It is an arithmetic number, because the mean of its divisors is an integer number (10254322).

Almost surely, 2^20508643 is an apocalyptic number.

20508643 is a deficient number, since it is larger than the sum of its proper divisors (1).

20508643 is an equidigital number, since it uses as much as digits as its factorization.

20508643 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5760, while the sum is 28.

The square root of 20508643 is about 4528.6469281674. The cubic root of 20508643 is about 273.7236411169.

The spelling of 20508643 in words is "twenty million, five hundred eight thousand, six hundred forty-three".