20645683217 has 2 divisors, whose sum is σ = 20645683218. Its totient is φ = 20645683216.

The previous prime is 20645683207. The next prime is 20645683249. The reversal of 20645683217 is 71238654602.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20645091856 + 591361 = 143684^2 + 769^2 .

It is a cyclic number.

It is not a de Polignac number, because 20645683217 - 2⁶ = 20645683153 is a prime.

It is not a weakly prime, because it can be changed into another prime (20645683207) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10322841608 + 10322841609.

It is an arithmetic number, because the mean of its divisors is an integer number (10322841609).

Almost surely, 2^20645683217 is an apocalyptic number.

It is an amenable number.

20645683217 is a deficient number, since it is larger than the sum of its proper divisors (1).

20645683217 is an equidigital number, since it uses as much as digits as its factorization.

20645683217 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 483840, while the sum is 44.

The spelling of 20645683217 in words is "twenty billion, six hundred forty-five million, six hundred eighty-three thousand, two hundred seventeen".