1968861661 has 12 divisors (see below), whose sum is σ = 2147549652. Its totient is φ = 1804123776.

The previous prime is 1968861641. The next prime is 1968861667. The reversal of 1968861661 is 1661688691.

It is a happy number.

It can be written as a sum of positive squares in 6 ways, for example, as 344288025 + 1624573636 = 18555^2 + 40306^2 .

It is a de Polignac number, because none of the positive numbers 2^k-1968861661 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1968861599 and 1968861608.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1968861667) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 19366 + ... + 65671.

It is an arithmetic number, because the mean of its divisors is an integer number (178962471).

Almost surely, 2^1968861661 is an apocalyptic number.

It is an amenable number.

1968861661 is a deficient number, since it is larger than the sum of its proper divisors (178687991).

1968861661 is a wasteful number, since it uses less digits than its factorization.

1968861661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 85200 (or 85187 counting only the distinct ones).

The product of its digits is 746496, while the sum is 52.

The square root of 1968861661 is about 44371.8566323295. The cubic root of 1968861661 is about 1253.3481781021.

The spelling of 1968861661 in words is "one billion, nine hundred sixty-eight million, eight hundred sixty-one thousand, six hundred sixty-one".