20644973 has 2 divisors, whose sum is σ = 20644974. Its totient is φ = 20644972.

The previous prime is 20644909. The next prime is 20644979. The reversal of 20644973 is 37944602.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20593444 + 51529 = 4538^2 + 227^2 .

It is a cyclic number.

It is not a de Polignac number, because 20644973 - 2⁶ = 20644909 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20644979) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10322486 + 10322487.

It is an arithmetic number, because the mean of its divisors is an integer number (10322487).

Almost surely, 2^20644973 is an apocalyptic number.

It is an amenable number.

20644973 is a deficient number, since it is larger than the sum of its proper divisors (1).

20644973 is an equidigital number, since it uses as much as digits as its factorization.

20644973 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 36288, while the sum is 35.

The square root of 20644973 is about 4543.6739539716. The cubic root of 20644973 is about 274.3288227316.

The spelling of 20644973 in words is "twenty million, six hundred forty-four thousand, nine hundred seventy-three".