1661313131 has 2 divisors, whose sum is σ = 1661313132. Its totient is φ = 1661313130.

The previous prime is 1661313119. The next prime is 1661313133. The reversal of 1661313131 is 1313131661.

It is a strong prime.

It is an emirp because it is prime and its reverse (1313131661) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1661313131 is a prime.

It is a super-2 number, since 2×1661313131² = 5519922638466046322, which contains 22 as substring.

Together with 1661313133, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1661313131.

It is not a weakly prime, because it can be changed into another prime (1661313133) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 830656565 + 830656566.

It is an arithmetic number, because the mean of its divisors is an integer number (830656566).

Almost surely, 2^1661313131 is an apocalyptic number.

1661313131 is a deficient number, since it is larger than the sum of its proper divisors (1).

1661313131 is an equidigital number, since it uses as much as digits as its factorization.

1661313131 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 972, while the sum is 26.

The square root of 1661313131 is about 40759.2091557233. The cubic root of 1661313131 is about 1184.3602761642.

Adding to 1661313131 its reverse (1313131661), we get a palindrome (2974444792).

The spelling of 1661313131 in words is "one billion, six hundred sixty-one million, three hundred thirteen thousand, one hundred thirty-one".