644674181 has 2 divisors, whose sum is σ = 644674182. Its totient is φ = 644674180.

The previous prime is 644674157. The next prime is 644674193. The reversal of 644674181 is 181476446.

644674181 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 545969956 + 98704225 = 23366^2 + 9935^2 .

It is a cyclic number.

It is not a de Polignac number, because 644674181 - 2⁶ = 644674117 is a prime.

It is a super-2 number, since 2×644674181² = 831209599296041522, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (644644181) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322337090 + 322337091.

It is an arithmetic number, because the mean of its divisors is an integer number (322337091).

Almost surely, 2^644674181 is an apocalyptic number.

It is an amenable number.

644674181 is a deficient number, since it is larger than the sum of its proper divisors (1).

644674181 is an equidigital number, since it uses as much as digits as its factorization.

644674181 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 129024, while the sum is 41.

The square root of 644674181 is about 25390.4348328263. The cubic root of 644674181 is about 863.8667512310.

The spelling of 644674181 in words is "six hundred forty-four million, six hundred seventy-four thousand, one hundred eighty-one".