990918999978 has 16 divisors (see below), whose sum is σ = 2035401189600. Its totient is φ = 321379135056.

The previous prime is 990918999971. The next prime is 990918999979. The reversal of 990918999978 is 879999819099.

It is a junction number, because it is equal to n+sod(n) for n = 990918999894 and 990918999903.

It is not an unprimeable number, because it can be changed into a prime (990918999971) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2231799328 + ... + 2231799771.

It is an arithmetic number, because the mean of its divisors is an integer number (127212574350).

Almost surely, 2^990918999978 is an apocalyptic number.

990918999978 is an abundant number, since it is smaller than the sum of its proper divisors (1044482189622).

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

990918999978 is a wasteful number, since it uses less digits than its factorization.

990918999978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4463599141.

The product of its (nonzero) digits is 2142770112, while the sum is 87.

The spelling of 990918999978 in words is "nine hundred ninety billion, nine hundred eighteen million, nine hundred ninety-nine thousand, nine hundred seventy-eight".