166221778351 has 2 divisors, whose sum is σ = 166221778352. Its totient is φ = 166221778350.

The previous prime is 166221778321. The next prime is 166221778363. The reversal of 166221778351 is 153877122661.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 166221778351 - 2¹³ = 166221770159 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 166221778295 and 166221778304.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (166221778321) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83110889175 + 83110889176.

It is an arithmetic number, because the mean of its divisors is an integer number (83110889176).

Almost surely, 2^166221778351 is an apocalyptic number.

166221778351 is a deficient number, since it is larger than the sum of its proper divisors (1).

166221778351 is an equidigital number, since it uses as much as digits as its factorization.

166221778351 is an evil number, because the sum of its binary digits is even.

The product of its digits is 846720, while the sum is 49.

The spelling of 166221778351 in words is "one hundred sixty-six billion, two hundred twenty-one million, seven hundred seventy-eight thousand, three hundred fifty-one".