1971378816 has 128 divisors (see below), whose sum is σ = 5782371840. Its totient is φ = 590085120.

The previous prime is 1971378809. The next prime is 1971378847. The reversal of 1971378816 is 6188731791.

It is a tau number, because it is divible by the number of its divisors (128).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 347781 + ... + 353403.

It is an arithmetic number, because the mean of its divisors is an integer number (45174780).

Almost surely, 2^1971378816 is an apocalyptic number.

1971378816 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1971378816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2891185920).

1971378816 is an abundant number, since it is smaller than the sum of its proper divisors (3810993024).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1971378816 is a wasteful number, since it uses less digits than its factorization.

1971378816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5734 (or 5722 counting only the distinct ones).

The product of its digits is 508032, while the sum is 51.

The square root of 1971378816 is about 44400.2118913863. The cubic root of 1971378816 is about 1253.8820785054.

The spelling of 1971378816 in words is "one billion, nine hundred seventy-one million, three hundred seventy-eight thousand, eight hundred sixteen".