978665640 has 128 divisors (see below), whose sum is σ = 3086899200. Its totient is φ = 247737600.

The previous prime is 978665603. The next prime is 978665647. The reversal of 978665640 is 46566879.

It is not an unprimeable number, because it can be changed into a prime (978665647) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 382365 + ... + 384915.

It is an arithmetic number, because the mean of its divisors is an integer number (24116400).

Almost surely, 2^978665640 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 978665640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1543449600).

978665640 is an abundant number, since it is smaller than the sum of its proper divisors (2108233560).

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

978665640 is a wasteful number, since it uses less digits than its factorization.

978665640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2727 (or 2723 counting only the distinct ones).

The product of its (nonzero) digits is 2177280, while the sum is 51.

The square root of 978665640 is about 31283.6321420643. The cubic root of 978665640 is about 992.8373658274.

The spelling of 978665640 in words is "nine hundred seventy-eight million, six hundred sixty-five thousand, six hundred forty".