2643378581 has 2 divisors, whose sum is σ = 2643378582. Its totient is φ = 2643378580.

The previous prime is 2643378571. The next prime is 2643378601. The reversal of 2643378581 is 1858733462.

2643378581 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1974380356 + 668998225 = 44434^2 + 25865^2 .

It is a cyclic number.

It is not a de Polignac number, because 2643378581 - 2²² = 2639184277 is a prime.

It is a super-2 number, since 2×2643378581² = 13974900644979147122, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2643378541) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1321689290 + 1321689291.

It is an arithmetic number, because the mean of its divisors is an integer number (1321689291).

Almost surely, 2^2643378581 is an apocalyptic number.

It is an amenable number.

2643378581 is a deficient number, since it is larger than the sum of its proper divisors (1).

2643378581 is an equidigital number, since it uses as much as digits as its factorization.

2643378581 is an evil number, because the sum of its binary digits is even.

The product of its digits is 967680, while the sum is 47.

The square root of 2643378581 is about 51413.7975741921. The cubic root of 2643378581 is about 1382.6739761022.

The spelling of 2643378581 in words is "two billion, six hundred forty-three million, three hundred seventy-eight thousand, five hundred eighty-one".