646722169 has 2 divisors, whose sum is σ = 646722170. Its totient is φ = 646722168.

The previous prime is 646722163. The next prime is 646722221. The reversal of 646722169 is 961227646.

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., 587432169 + 59290000 = 24237^2 + 7700^2 .

It is a cyclic number.

It is not a de Polignac number, because 646722169 - 2¹¹ = 646720121 is a prime.

It is a super-2 number, since 2×646722169² = 836499127752129122, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (646722163) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 323361084 + 323361085.

It is an arithmetic number, because the mean of its divisors is an integer number (323361085).

Almost surely, 2^646722169 is an apocalyptic number.

It is an amenable number.

646722169 is a deficient number, since it is larger than the sum of its proper divisors (1).

646722169 is an equidigital number, since it uses as much as digits as its factorization.

646722169 is an evil number, because the sum of its binary digits is even.

The product of its digits is 217728, while the sum is 43.

The square root of 646722169 is about 25430.7327656912. The cubic root of 646722169 is about 864.7805557804.

The spelling of 646722169 in words is "six hundred forty-six million, seven hundred twenty-two thousand, one hundred sixty-nine".