20641993 has 2 divisors, whose sum is σ = 20641994. Its totient is φ = 20641992.

The previous prime is 20641987. The next prime is 20642009. The reversal of 20641993 is 39914602.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20142144 + 499849 = 4488^2 + 707^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20641993 is a prime.

It is not a weakly prime, because it can be changed into another prime (20641913) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10320996 + 10320997.

It is an arithmetic number, because the mean of its divisors is an integer number (10320997).

Almost surely, 2^20641993 is an apocalyptic number.

It is an amenable number.

20641993 is a deficient number, since it is larger than the sum of its proper divisors (1).

20641993 is an equidigital number, since it uses as much as digits as its factorization.

20641993 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 11664, while the sum is 34.

The square root of 20641993 is about 4543.3460136776. The cubic root of 20641993 is about 274.3156227591.

The spelling of 20641993 in words is "twenty million, six hundred forty-one thousand, nine hundred ninety-three".