1921078816 has 24 divisors (see below), whose sum is σ = 3794227164. Its totient is φ = 957465600.

The previous prime is 1921078811. The next prime is 1921078849. The reversal of 1921078816 is 6188701291.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 1101974416 + 819104400 = 33196^2 + 28620^2 .

It is not an unprimeable number, because it can be changed into a prime (1921078811) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 85885 + ... + 105916.

Almost surely, 2^1921078816 is an apocalyptic number.

1921078816 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

It is an amenable number.

1921078816 is a deficient number, since it is larger than the sum of its proper divisors (1873148348).

1921078816 is a wasteful number, since it uses less digits than its factorization.

1921078816 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 192124 (or 192116 counting only the distinct ones).

The product of its (nonzero) digits is 48384, while the sum is 43.

The square root of 1921078816 is about 43830.1131187224. The cubic root of 1921078816 is about 1243.1257457498.

The spelling of 1921078816 in words is "one billion, nine hundred twenty-one million, seventy-eight thousand, eight hundred sixteen".