20918543 has 4 divisors (see below), whose sum is σ = 20930088. Its totient is φ = 20907000.

The previous prime is 20918533. The next prime is 20918567. The reversal of 20918543 is 34581902.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 20918543 - 2⁶ = 20918479 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20918533) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2396 + ... + 6897.

It is an arithmetic number, because the mean of its divisors is an integer number (5232522).

Almost surely, 2^20918543 is an apocalyptic number.

20918543 is a deficient number, since it is larger than the sum of its proper divisors (11545).

20918543 is an equidigital number, since it uses as much as digits as its factorization.

20918543 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11544.

The product of its (nonzero) digits is 8640, while the sum is 32.

The square root of 20918543 is about 4573.6793722341. The cubic root of 20918543 is about 275.5352352763.

The spelling of 20918543 in words is "twenty million, nine hundred eighteen thousand, five hundred forty-three".