999978920 has 32 divisors (see below), whose sum is σ = 2263770720. Its totient is φ = 397535040.

The previous prime is 999978901. The next prime is 999978929. The reversal of 999978920 is 29879999.

It is not an unprimeable number, because it can be changed into a prime (999978929) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 70166 + ... + 83205.

It is an arithmetic number, because the mean of its divisors is an integer number (70742835).

Almost surely, 2^999978920 is an apocalyptic number.

It is an amenable number.

999978920 is an abundant number, since it is smaller than the sum of its proper divisors (1263791800).

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

999978920 is a wasteful number, since it uses less digits than its factorization.

999978920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 153545 (or 153541 counting only the distinct ones).

The product of its (nonzero) digits is 6613488, while the sum is 62.

The square root of 999978920 is about 31622.4432958619. The cubic root of 999978920 is about 999.9929732840.

The spelling of 999978920 in words is "nine hundred ninety-nine million, nine hundred seventy-eight thousand, nine hundred twenty".