1923978661 has 16 divisors (see below), whose sum is σ = 2138185728. Its totient is φ = 1716548400.

The previous prime is 1923978631. The next prime is 1923978673. The reversal of 1923978661 is 1668793291.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 1923978661 - 2⁷ = 1923978533 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1923978599 and 1923978608.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1923978631) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 168640 + ... + 179686.

It is an arithmetic number, because the mean of its divisors is an integer number (133636608).

Almost surely, 2^1923978661 is an apocalyptic number.

1923978661 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1923978661 is a deficient number, since it is larger than the sum of its proper divisors (214207067).

1923978661 is a wasteful number, since it uses less digits than its factorization.

1923978661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11352.

The product of its digits is 979776, while the sum is 52.

The square root of 1923978661 is about 43863.1811545857. The cubic root of 1923978661 is about 1243.7509256628.

The spelling of 1923978661 in words is "one billion, nine hundred twenty-three million, nine hundred seventy-eight thousand, six hundred sixty-one".