20643893 has 2 divisors, whose sum is σ = 20643894. Its totient is φ = 20643892.

The previous prime is 20643851. The next prime is 20643907. The reversal of 20643893 is 39834602.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19909444 + 734449 = 4462^2 + 857^2 .

It is a cyclic number.

It is not a de Polignac number, because 20643893 - 2¹⁶ = 20578357 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20648893) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10321946 + 10321947.

It is an arithmetic number, because the mean of its divisors is an integer number (10321947).

Almost surely, 2^20643893 is an apocalyptic number.

It is an amenable number.

20643893 is a deficient number, since it is larger than the sum of its proper divisors (1).

20643893 is an equidigital number, since it uses as much as digits as its factorization.

20643893 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 31104, while the sum is 35.

The square root of 20643893 is about 4543.5551058615. Note that the first 3 decimals coincide. The cubic root of 20643893 is about 274.3240389957.

The spelling of 20643893 in words is "twenty million, six hundred forty-three thousand, eight hundred ninety-three".