20512216217 has 2 divisors, whose sum is σ = 20512216218. Its totient is φ = 20512216216.

The previous prime is 20512216189. The next prime is 20512216223. The reversal of 20512216217 is 71261221502.

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., 19492627456 + 1019588761 = 139616^2 + 31931^2 .

It is a cyclic number.

It is not a de Polignac number, because 20512216217 - 2²² = 20508021913 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20512216217.

It is not a weakly prime, because it can be changed into another prime (20512216817) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10256108108 + 10256108109.

It is an arithmetic number, because the mean of its divisors is an integer number (10256108109).

Almost surely, 2^20512216217 is an apocalyptic number.

It is an amenable number.

20512216217 is a deficient number, since it is larger than the sum of its proper divisors (1).

20512216217 is an equidigital number, since it uses as much as digits as its factorization.

20512216217 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3360, while the sum is 29.

Adding to 20512216217 its reverse (71261221502), we get a palindrome (91773437719).

The spelling of 20512216217 in words is "twenty billion, five hundred twelve million, two hundred sixteen thousand, two hundred seventeen".