999636990 has 64 divisors (see below), whose sum is σ = 2681102592. Its totient is φ = 236422400.

The previous prime is 999636959. The next prime is 999636991. The reversal of 999636990 is 99636999.

It is a super-2 number, since 2×999636990² = 1998548223552520200, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (999636991) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 23412 + ... + 50471.

It is an arithmetic number, because the mean of its divisors is an integer number (41892228).

Almost surely, 2^999636990 is an apocalyptic number.

999636990 is an abundant number, since it is smaller than the sum of its proper divisors (1681465602).

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

999636990 is a wasteful number, since it uses less digits than its factorization.

999636990 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 73945.

The product of its (nonzero) digits is 6377292, while the sum is 60.

The square root of 999636990 is about 31617.0363886307. The cubic root of 999636990 is about 999.8789820219.

It can be divided in two parts, 99963 and 6990, that added together give a triangular number (106953 = T₄₆₂).

The spelling of 999636990 in words is "nine hundred ninety-nine million, six hundred thirty-six thousand, nine hundred ninety".