20643019 has 4 divisors (see below), whose sum is σ = 20652280. Its totient is φ = 20633760.

The previous prime is 20642971. The next prime is 20643043. The reversal of 20643019 is 91034602.

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 20643019 - 2¹⁵ = 20610251 is a prime.

It is a super-2 number, since 2×20643019² = 852268466868722, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20642984 and 20643002.

It is not an unprimeable number, because it can be changed into a prime (20640019) 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, 979 + ... + 6499.

It is an arithmetic number, because the mean of its divisors is an integer number (5163070).

Almost surely, 2^20643019 is an apocalyptic number.

20643019 is a deficient number, since it is larger than the sum of its proper divisors (9261).

20643019 is an equidigital number, since it uses as much as digits as its factorization.

20643019 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9260.

The product of its (nonzero) digits is 1296, while the sum is 25.

The square root of 20643019 is about 4543.4589246520. The cubic root of 20643019 is about 274.3201675910.

The spelling of 20643019 in words is "twenty million, six hundred forty-three thousand, nineteen".