20840543 has 2 divisors, whose sum is σ = 20840544. Its totient is φ = 20840542.

The previous prime is 20840537. The next prime is 20840557. The reversal of 20840543 is 34504802.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20840543 - 2⁴ = 20840527 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20840503) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10420271 + 10420272.

It is an arithmetic number, because the mean of its divisors is an integer number (10420272).

Almost surely, 2^20840543 is an apocalyptic number.

20840543 is a deficient number, since it is larger than the sum of its proper divisors (1).

20840543 is an equidigital number, since it uses as much as digits as its factorization.

20840543 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3840, while the sum is 26.

The square root of 20840543 is about 4565.1443569727. The cubic root of 20840543 is about 275.1923414735.

The spelling of 20840543 in words is "twenty million, eight hundred forty thousand, five hundred forty-three".