999155989440 has 504 divisors, whose sum is σ = 4006595737872. Its totient is φ = 227874447360.

The previous prime is 999155989417. The next prime is 999155989483. The reversal of 999155989440 is 44989551999.

999155989440 is a `hidden beast` number, since 9 + 9 + 91 + 5 + 5 + 98 + 9 + 440 = 666.

It is a tau number, because it is divible by the number of its divisors (504).

It is a Harshad number since it is a multiple of its sum of digits (72).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 65895460 + ... + 65910620.

It is an arithmetic number, because the mean of its divisors is an integer number (7949594718).

Almost surely, 2^999155989440 is an apocalyptic number.

999155989440 is a gapful number since it is divisible by the number (90) 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 999155989440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2003297868936).

999155989440 is an abundant number, since it is smaller than the sum of its proper divisors (3007439748432).

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

999155989440 is a wasteful number, since it uses less digits than its factorization.

999155989440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15665 (or 15645 counting only the distinct ones).

The product of its (nonzero) digits is 188956800, while the sum is 72.

The spelling of 999155989440 in words is "nine hundred ninety-nine billion, one hundred fifty-five million, nine hundred eighty-nine thousand, four hundred forty".