20643123 has 4 divisors (see below), whose sum is σ = 27524168. Its totient is φ = 13762080.

The previous prime is 20643109. The next prime is 20643127. The reversal of 20643123 is 32134602.

It is a happy number.

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

It is not a de Polignac number, because 20643123 - 2⁴ = 20643107 is a prime.

It is a super-2 number, since 2×20643123² = 852277054386258, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20643123.

It is not an unprimeable number, because it can be changed into a prime (20643127) 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, 3440518 + ... + 3440523.

It is an arithmetic number, because the mean of its divisors is an integer number (6881042).

Almost surely, 2^20643123 is an apocalyptic number.

20643123 is a deficient number, since it is larger than the sum of its proper divisors (6881045).

20643123 is an equidigital number, since it uses as much as digits as its factorization.

20643123 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6881044.

The product of its (nonzero) digits is 864, while the sum is 21.

The square root of 20643123 is about 4543.4703696624. The cubic root of 20643123 is about 274.3206282673.

Adding to 20643123 its reverse (32134602), we get a palindrome (52777725).

The spelling of 20643123 in words is "twenty million, six hundred forty-three thousand, one hundred twenty-three".