216521364253 has 2 divisors, whose sum is σ = 216521364254. Its totient is φ = 216521364252.

The previous prime is 216521364193. The next prime is 216521364271. The reversal of 216521364253 is 352463125612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 210179153209 + 6342211044 = 458453^2 + 79638^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-216521364253 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (216521367253) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108260682126 + 108260682127.

It is an arithmetic number, because the mean of its divisors is an integer number (108260682127).

Almost surely, 2^216521364253 is an apocalyptic number.

It is an amenable number.

216521364253 is a deficient number, since it is larger than the sum of its proper divisors (1).

216521364253 is an equidigital number, since it uses as much as digits as its factorization.

216521364253 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 259200, while the sum is 40.

Adding to 216521364253 its reverse (352463125612), we get a palindrome (568984489865).

The spelling of 216521364253 in words is "two hundred sixteen billion, five hundred twenty-one million, three hundred sixty-four thousand, two hundred fifty-three".