20553643 has 4 divisors (see below), whose sum is σ = 22422168. Its totient is φ = 18685120.

The previous prime is 20553623. The next prime is 20553647. The reversal of 20553643 is 34635502.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20553643 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20553647) 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, 934246 + ... + 934267.

It is an arithmetic number, because the mean of its divisors is an integer number (5605542).

Almost surely, 2^20553643 is an apocalyptic number.

20553643 is a deficient number, since it is larger than the sum of its proper divisors (1868525).

20553643 is a wasteful number, since it uses less digits than its factorization.

20553643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1868524.

The product of its (nonzero) digits is 10800, while the sum is 28.

The square root of 20553643 is about 4533.6125771839. The cubic root of 20553643 is about 273.9236960525.

The spelling of 20553643 in words is "twenty million, five hundred fifty-three thousand, six hundred forty-three".