556261991 has 2 divisors, whose sum is σ = 556261992. Its totient is φ = 556261990.

The previous prime is 556261907. The next prime is 556261997. The reversal of 556261991 is 199162655.

556261991 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 556261991 - 2²⁶ = 489153127 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (556261997) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 278130995 + 278130996.

It is an arithmetic number, because the mean of its divisors is an integer number (278130996).

Almost surely, 2^556261991 is an apocalyptic number.

556261991 is a deficient number, since it is larger than the sum of its proper divisors (1).

556261991 is an equidigital number, since it uses as much as digits as its factorization.

556261991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 145800, while the sum is 44.

The square root of 556261991 is about 23585.2070374631. The cubic root of 556261991 is about 822.4189877804.

The spelling of 556261991 in words is "five hundred fifty-six million, two hundred sixty-one thousand, nine hundred ninety-one".