10661121661 has 2 divisors, whose sum is σ = 10661121662. Its totient is φ = 10661121660.

The previous prime is 10661121659. The next prime is 10661121677. The reversal of 10661121661 is 16612116601.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 7305120900 + 3356000761 = 85470^2 + 57931^2 .

It is a cyclic number.

It is not a de Polignac number, because 10661121661 - 2¹ = 10661121659 is a prime.

It is a super-2 number, since 2×10661121661² (a number of 21 digits) contains 22 as substring.

Together with 10661121659, 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 (10661121631) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5330560830 + 5330560831.

It is an arithmetic number, because the mean of its divisors is an integer number (5330560831).

Almost surely, 2^10661121661 is an apocalyptic number.

It is an amenable number.

10661121661 is a deficient number, since it is larger than the sum of its proper divisors (1).

10661121661 is an equidigital number, since it uses as much as digits as its factorization.

10661121661 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2592, while the sum is 31.

The spelling of 10661121661 in words is "ten billion, six hundred sixty-one million, one hundred twenty-one thousand, six hundred sixty-one".