1561333231 has 2 divisors, whose sum is σ = 1561333232. Its totient is φ = 1561333230.

The previous prime is 1561333229. The next prime is 1561333237. The reversal of 1561333231 is 1323331651.

It is a weak prime.

It is an emirp because it is prime and its reverse (1323331651) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1561333231 - 2¹ = 1561333229 is a prime.

It is a super-2 number, since 2×1561333231² = 4875522916449798722, which contains 22 as substring.

Together with 1561333229, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 1561333231.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1561333237) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 780666615 + 780666616.

It is an arithmetic number, because the mean of its divisors is an integer number (780666616).

Almost surely, 2^1561333231 is an apocalyptic number.

1561333231 is a deficient number, since it is larger than the sum of its proper divisors (1).

1561333231 is an equidigital number, since it uses as much as digits as its factorization.

1561333231 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4860, while the sum is 28.

The square root of 1561333231 is about 39513.7094057240. The cubic root of 1561333231 is about 1160.1083011745.

Adding to 1561333231 its reverse (1323331651), we get a palindrome (2884664882).

The spelling of 1561333231 in words is "one billion, five hundred sixty-one million, three hundred thirty-three thousand, two hundred thirty-one".