999986640 has 80 divisors (see below), whose sum is σ = 3234757248. Its totient is φ = 255067648.

The previous prime is 999986639. The next prime is 999986641. The reversal of 999986640 is 46689999.

It is an interprime number because it is at equal distance from previous prime (999986639) and next prime (999986641).

It is a tau number, because it is divible by the number of its divisors (80).

It is a Harshad number since it is a multiple of its sum of digits (60).

It is a nialpdrome in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (999986641) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 85059 + ... + 96098.

Almost surely, 2^999986640 is an apocalyptic number.

It is an amenable number.

999986640 is an abundant number, since it is smaller than the sum of its proper divisors (2234770608).

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

999986640 is a wasteful number, since it uses less digits than its factorization.

999986640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 181196 (or 181190 counting only the distinct ones).

The product of its (nonzero) digits is 7558272, while the sum is 60.

The square root of 999986640 is about 31622.5653608305. The cubic root of 999986640 is about 999.9955466468.

The spelling of 999986640 in words is "nine hundred ninety-nine million, nine hundred eighty-six thousand, six hundred forty".