2543667821 has 2 divisors, whose sum is σ = 2543667822. Its totient is φ = 2543667820.

The previous prime is 2543667817. The next prime is 2543667859. The reversal of 2543667821 is 1287663452.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 2217468100 + 326199721 = 47090^2 + 18061^2 .

It is a cyclic number.

It is not a de Polignac number, because 2543667821 - 2² = 2543667817 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2543664821) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1271833910 + 1271833911.

It is an arithmetic number, because the mean of its divisors is an integer number (1271833911).

Almost surely, 2^2543667821 is an apocalyptic number.

It is an amenable number.

2543667821 is a deficient number, since it is larger than the sum of its proper divisors (1).

2543667821 is an equidigital number, since it uses as much as digits as its factorization.

2543667821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 483840, while the sum is 44.

The square root of 2543667821 is about 50434.7878056407. The cubic root of 2543667821 is about 1365.0654203462.

The spelling of 2543667821 in words is "two billion, five hundred forty-three million, six hundred sixty-seven thousand, eight hundred twenty-one".