65628516221 has 2 divisors, whose sum is σ = 65628516222. Its totient is φ = 65628516220.

The previous prime is 65628516199. The next prime is 65628516263. The reversal of 65628516221 is 12261582656.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 61499040100 + 4129476121 = 247990^2 + 64261^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-65628516221 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (65628516281) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 32814258110 + 32814258111.

It is an arithmetic number, because the mean of its divisors is an integer number (32814258111).

Almost surely, 2^65628516221 is an apocalyptic number.

It is an amenable number.

65628516221 is a deficient number, since it is larger than the sum of its proper divisors (1).

65628516221 is an equidigital number, since it uses as much as digits as its factorization.

65628516221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 345600, while the sum is 44.

The spelling of 65628516221 in words is "sixty-five billion, six hundred twenty-eight million, five hundred sixteen thousand, two hundred twenty-one".