1612172166221 has 2 divisors, whose sum is σ = 1612172166222. Its totient is φ = 1612172166220.

The previous prime is 1612172166203. The next prime is 1612172166329. The reversal of 1612172166221 is 1226612712161.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1034260524196 + 577911642025 = 1016986^2 + 760205^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1612172166221 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1612172166421) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 806086083110 + 806086083111.

It is an arithmetic number, because the mean of its divisors is an integer number (806086083111).

Almost surely, 2^{1612172166221} is an apocalyptic number.

It is an amenable number.

1612172166221 is a deficient number, since it is larger than the sum of its proper divisors (1).

1612172166221 is an equidigital number, since it uses as much as digits as its factorization.

1612172166221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 24192, while the sum is 38.

Adding to 1612172166221 its reverse (1226612712161), we get a palindrome (2838784878382).

The spelling of 1612172166221 in words is "one trillion, six hundred twelve billion, one hundred seventy-two million, one hundred sixty-six thousand, two hundred twenty-one".