1261566443 has 2 divisors, whose sum is σ = 1261566444. Its totient is φ = 1261566442.

The previous prime is 1261566431. The next prime is 1261566499. The reversal of 1261566443 is 3446651621.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1261566443 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1261566397 and 1261566406.

It is not a weakly prime, because it can be changed into another prime (1261566743) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 630783221 + 630783222.

It is an arithmetic number, because the mean of its divisors is an integer number (630783222).

Almost surely, 2^1261566443 is an apocalyptic number.

1261566443 is a deficient number, since it is larger than the sum of its proper divisors (1).

1261566443 is an equidigital number, since it uses as much as digits as its factorization.

1261566443 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 103680, while the sum is 38.

The square root of 1261566443 is about 35518.5366111837. The cubic root of 1261566443 is about 1080.5297021485.

The spelling of 1261566443 in words is "one billion, two hundred sixty-one million, five hundred sixty-six thousand, four hundred forty-three".