643415581 has 2 divisors, whose sum is σ = 643415582. Its totient is φ = 643415580.

The previous prime is 643415573. The next prime is 643415587. The reversal of 643415581 is 185514346.

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., 387735481 + 255680100 = 19691^2 + 15990^2 .

It is a cyclic number.

It is not a de Polignac number, because 643415581 - 2³ = 643415573 is a prime.

It is a super-2 number, since 2×643415581² = 827967219747135122, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 643415581.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (643415587) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321707790 + 321707791.

It is an arithmetic number, because the mean of its divisors is an integer number (321707791).

Almost surely, 2^643415581 is an apocalyptic number.

It is an amenable number.

643415581 is a deficient number, since it is larger than the sum of its proper divisors (1).

643415581 is an equidigital number, since it uses as much as digits as its factorization.

643415581 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 57600, while the sum is 37.

The square root of 643415581 is about 25365.6377999845. The cubic root of 643415581 is about 863.3042081411.

The spelling of 643415581 in words is "six hundred forty-three million, four hundred fifteen thousand, five hundred eighty-one".