9901839978 has 20 divisors (see below), whose sum is σ = 22187456610. Its totient is φ = 3300613272.

The previous prime is 9901839977. The next prime is 9901840037. The reversal of 9901839978 is 8799381099.

It can be written as a sum of positive squares in only one way, i.e., 8588284929 + 1313555049 = 92673^2 + 36243^2 .

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (9901839977) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 30561073 + ... + 30561396.

Almost surely, 2^9901839978 is an apocalyptic number.

9901839978 is an abundant number, since it is smaller than the sum of its proper divisors (12285616632).

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

9901839978 is a wasteful number, since it uses less digits than its factorization.

9901839978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 61122483 (or 61122474 counting only the distinct ones).

The product of its (nonzero) digits is 8817984, while the sum is 63.

The square root of 9901839978 is about 99507.9895184301. The cubic root of 9901839978 is about 2147.3621861803.

The spelling of 9901839978 in words is "nine billion, nine hundred one million, eight hundred thirty-nine thousand, nine hundred seventy-eight".