644147473 has 2 divisors, whose sum is σ = 644147474. Its totient is φ = 644147472.

The previous prime is 644147423. The next prime is 644147489. The reversal of 644147473 is 374741446.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 522442449 + 121705024 = 22857^2 + 11032^2 .

It is a cyclic number.

It is not a de Polignac number, because 644147473 - 2¹³ = 644139281 is a prime.

It is not a weakly prime, because it can be changed into another prime (644147423) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322073736 + 322073737.

It is an arithmetic number, because the mean of its divisors is an integer number (322073737).

Almost surely, 2^644147473 is an apocalyptic number.

It is an amenable number.

644147473 is a deficient number, since it is larger than the sum of its proper divisors (1).

644147473 is an equidigital number, since it uses as much as digits as its factorization.

644147473 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 225792, while the sum is 40.

The square root of 644147473 is about 25380.0605397229. The cubic root of 644147473 is about 863.6314233120.

The spelling of 644147473 in words is "six hundred forty-four million, one hundred forty-seven thousand, four hundred seventy-three".