2556781349 has 2 divisors, whose sum is σ = 2556781350. Its totient is φ = 2556781348.

The previous prime is 2556781319. The next prime is 2556781373. The reversal of 2556781349 is 9431876552.

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., 2287230625 + 269550724 = 47825^2 + 16418^2 .

It is a cyclic number.

It is not a de Polignac number, because 2556781349 - 2²⁴ = 2540004133 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 2556781297 and 2556781306.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2556781309) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1278390674 + 1278390675.

It is an arithmetic number, because the mean of its divisors is an integer number (1278390675).

Almost surely, 2^2556781349 is an apocalyptic number.

It is an amenable number.

2556781349 is a deficient number, since it is larger than the sum of its proper divisors (1).

2556781349 is an equidigital number, since it uses as much as digits as its factorization.

2556781349 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1814400, while the sum is 50.

The square root of 2556781349 is about 50564.6254707775. The cubic root of 2556781349 is about 1367.4072027553.

The spelling of 2556781349 in words is "two billion, five hundred fifty-six million, seven hundred eighty-one thousand, three hundred forty-nine".