11531133661 has 2 divisors, whose sum is σ = 11531133662. Its totient is φ = 11531133660.

The previous prime is 11531133659. The next prime is 11531133689. The reversal of 11531133661 is 16633113511.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11493126436 + 38007225 = 107206^2 + 6165^2 .

It is a cyclic number.

It is not a de Polignac number, because 11531133661 - 2¹ = 11531133659 is a prime.

Together with 11531133659, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (11531133631) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5765566830 + 5765566831.

It is an arithmetic number, because the mean of its divisors is an integer number (5765566831).

Almost surely, 2^11531133661 is an apocalyptic number.

It is an amenable number.

11531133661 is a deficient number, since it is larger than the sum of its proper divisors (1).

11531133661 is an equidigital number, since it uses as much as digits as its factorization.

11531133661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4860, while the sum is 31.

The spelling of 11531133661 in words is "eleven billion, five hundred thirty-one million, one hundred thirty-three thousand, six hundred sixty-one".