20290643 has 4 divisors (see below), whose sum is σ = 20402928. Its totient is φ = 20178360.

The previous prime is 20290609. The next prime is 20290649. The reversal of 20290643 is 34609202.

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 20290643 - 2⁶ = 20290579 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20290649) 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, 55871 + ... + 56232.

It is an arithmetic number, because the mean of its divisors is an integer number (5100732).

Almost surely, 2^20290643 is an apocalyptic number.

20290643 is a deficient number, since it is larger than the sum of its proper divisors (112285).

20290643 is a wasteful number, since it uses less digits than its factorization.

20290643 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 112284.

The product of its (nonzero) digits is 2592, while the sum is 26.

The square root of 20290643 is about 4504.5136252430. The cubic root of 20290643 is about 272.7503207222.

Adding to 20290643 its reverse (34609202), we get a palindrome (54899845).

The spelling of 20290643 in words is "twenty million, two hundred ninety thousand, six hundred forty-three".