2556403391 has 2 divisors, whose sum is σ = 2556403392. Its totient is φ = 2556403390.

The previous prime is 2556403303. The next prime is 2556403411. The reversal of 2556403391 is 1933046552.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2556403391 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2556403691) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1278201695 + 1278201696.

It is an arithmetic number, because the mean of its divisors is an integer number (1278201696).

Almost surely, 2^2556403391 is an apocalyptic number.

2556403391 is a deficient number, since it is larger than the sum of its proper divisors (1).

2556403391 is an equidigital number, since it uses as much as digits as its factorization.

2556403391 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 97200, while the sum is 38.

The square root of 2556403391 is about 50560.8879569970. The cubic root of 2556403391 is about 1367.3398201246.

The spelling of 2556403391 in words is "two billion, five hundred fifty-six million, four hundred three thousand, three hundred ninety-one".