1231066591 has 2 divisors, whose sum is σ = 1231066592. Its totient is φ = 1231066590.

The previous prime is 1231066583. The next prime is 1231066619. The reversal of 1231066591 is 1956601321.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1231066591 - 2³ = 1231066583 is a prime.

It is a super-3 number, since 3×1231066591³ (a number of 28 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1231066511) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 615533295 + 615533296.

It is an arithmetic number, because the mean of its divisors is an integer number (615533296).

Almost surely, 2^1231066591 is an apocalyptic number.

1231066591 is a deficient number, since it is larger than the sum of its proper divisors (1).

1231066591 is an equidigital number, since it uses as much as digits as its factorization.

1231066591 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 9720, while the sum is 34.

The square root of 1231066591 is about 35086.5585516733. The cubic root of 1231066591 is about 1071.7508792984.

The spelling of 1231066591 in words is "one billion, two hundred thirty-one million, sixty-six thousand, five hundred ninety-one".