1261138859 has 2 divisors, whose sum is σ = 1261138860. Its totient is φ = 1261138858.

The previous prime is 1261138847. The next prime is 1261138861. The reversal of 1261138859 is 9588311621.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1261138859 is a prime.

Together with 1261138861, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (1261158859) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 630569429 + 630569430.

It is an arithmetic number, because the mean of its divisors is an integer number (630569430).

Almost surely, 2^1261138859 is an apocalyptic number.

1261138859 is a deficient number, since it is larger than the sum of its proper divisors (1).

1261138859 is an equidigital number, since it uses as much as digits as its factorization.

1261138859 is an evil number, because the sum of its binary digits is even.

The product of its digits is 103680, while the sum is 44.

The square root of 1261138859 is about 35512.5169341741. The cubic root of 1261138859 is about 1080.4076133432.

The spelling of 1261138859 in words is "one billion, two hundred sixty-one million, one hundred thirty-eight thousand, eight hundred fifty-nine".