20645543 has 4 divisors (see below), whose sum is σ = 20838600. Its totient is φ = 20452488.

The previous prime is 20645539. The next prime is 20645551. The reversal of 20645543 is 34554602.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20645543 - 2² = 20645539 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 (20645843) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 96368 + ... + 96581.

It is an arithmetic number, because the mean of its divisors is an integer number (5209650).

Almost surely, 2^20645543 is an apocalyptic number.

20645543 is a deficient number, since it is larger than the sum of its proper divisors (193057).

20645543 is a wasteful number, since it uses less digits than its factorization.

20645543 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 193056.

The product of its (nonzero) digits is 14400, while the sum is 29.

The square root of 20645543 is about 4543.7366781098. The cubic root of 20645543 is about 274.3313474139.

The spelling of 20645543 in words is "twenty million, six hundred forty-five thousand, five hundred forty-three".