20538643 has 2 divisors, whose sum is σ = 20538644. Its totient is φ = 20538642.

The previous prime is 20538631. The next prime is 20538673. The reversal of 20538643 is 34683502.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20538643 - 2⁵ = 20538611 is a prime.

It is not a weakly prime, because it can be changed into another prime (20538673) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10269321 + 10269322.

It is an arithmetic number, because the mean of its divisors is an integer number (10269322).

Almost surely, 2^20538643 is an apocalyptic number.

20538643 is a deficient number, since it is larger than the sum of its proper divisors (1).

20538643 is an equidigital number, since it uses as much as digits as its factorization.

20538643 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 17280, while the sum is 31.

The square root of 20538643 is about 4531.9579653832. The cubic root of 20538643 is about 273.8570435473.

The spelling of 20538643 in words is "twenty million, five hundred thirty-eight thousand, six hundred forty-three".