20640313 has 2 divisors, whose sum is σ = 20640314. Its totient is φ = 20640312.

The previous prime is 20640307. The next prime is 20640317. The reversal of 20640313 is 31304602.

20640313 = 3212² + 3213².

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 10323369 + 10316944 = 3213^2 + 3212^2 .

It is a cyclic number.

It is not a de Polignac number, because 20640313 - 2¹⁷ = 20509241 is a prime.

It is not a weakly prime, because it can be changed into another prime (20640317) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10320156 + 10320157.

It is an arithmetic number, because the mean of its divisors is an integer number (10320157).

Almost surely, 2^20640313 is an apocalyptic number.

20640313 is the 3213-rd centered square number.

It is an amenable number.

20640313 is a deficient number, since it is larger than the sum of its proper divisors (1).

20640313 is an equidigital number, since it uses as much as digits as its factorization.

20640313 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 432, while the sum is 19.

The square root of 20640313 is about 4543.1611241513. The cubic root of 20640313 is about 274.3081806039.

Adding to 20640313 its reverse (31304602), we get a palindrome (51944915).

The spelling of 20640313 in words is "twenty million, six hundred forty thousand, three hundred thirteen".