2543656691 has 2 divisors, whose sum is σ = 2543656692. Its totient is φ = 2543656690.

The previous prime is 2543656663. The next prime is 2543656727. The reversal of 2543656691 is 1966563452.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 2543656691 - 2⁶ = 2543656627 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (2543656631) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1271828345 + 1271828346.

It is an arithmetic number, because the mean of its divisors is an integer number (1271828346).

Almost surely, 2^2543656691 is an apocalyptic number.

2543656691 is a deficient number, since it is larger than the sum of its proper divisors (1).

2543656691 is an equidigital number, since it uses as much as digits as its factorization.

2543656691 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1166400, while the sum is 47.

The square root of 2543656691 is about 50434.6774650141. The cubic root of 2543656691 is about 1365.0634293630.

The spelling of 2543656691 in words is "two billion, five hundred forty-three million, six hundred fifty-six thousand, six hundred ninety-one".