20643407 has 2 divisors, whose sum is σ = 20643408. Its totient is φ = 20643406.

The previous prime is 20643379. The next prime is 20643421. The reversal of 20643407 is 70434602.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20643407 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20643487) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10321703 + 10321704.

It is an arithmetic number, because the mean of its divisors is an integer number (10321704).

Almost surely, 2^20643407 is an apocalyptic number.

20643407 is a deficient number, since it is larger than the sum of its proper divisors (1).

20643407 is an equidigital number, since it uses as much as digits as its factorization.

20643407 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4032, while the sum is 26.

The square root of 20643407 is about 4543.5016231977. The cubic root of 20643407 is about 274.3218862601.

The spelling of 20643407 in words is "twenty million, six hundred forty-three thousand, four hundred seven".