999980640 has 480 divisors, whose sum is σ = 3863946240. Its totient is φ = 242611200.

The previous prime is 999980633. The next prime is 999980651. The reversal of 999980640 is 46089999.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (480).

It is a super-2 number, since 2×999980640² = 1999922560749619200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 7633375 + ... + 7633505.

It is an arithmetic number, because the mean of its divisors is an integer number (8049888).

Almost surely, 2^999980640 is an apocalyptic number.

999980640 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 999980640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1931973120).

999980640 is an abundant number, since it is smaller than the sum of its proper divisors (2863965600).

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

999980640 is a wasteful number, since it uses less digits than its factorization.

999980640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 208 (or 191 counting only the distinct ones).

The product of its (nonzero) digits is 1259712, while the sum is 54.

The square root of 999980640 is about 31622.4704917247. The cubic root of 999980640 is about 999.9935466250.

The spelling of 999980640 in words is "nine hundred ninety-nine million, nine hundred eighty thousand, six hundred forty".