16509990 has 64 divisors (see below), whose sum is σ = 46863360. Its totient is φ = 3642240.

The previous prime is 16509989. The next prime is 16509991. The reversal of 16509990 is 9990561.

It is an interprime number because it is at equal distance from previous prime (16509989) and next prime (16509991).

It is a Smith number, since the sum of its digits (39) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16509991) 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, 4735 + ... + 7445.

It is an arithmetic number, because the mean of its divisors is an integer number (732240).

Almost surely, 2^16509990 is an apocalyptic number.

16509990 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 16509990, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23431680).

16509990 is an abundant number, since it is smaller than the sum of its proper divisors (30353370).

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

16509990 is a wasteful number, since it uses less digits than its factorization.

16509990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2757.

The product of its (nonzero) digits is 21870, while the sum is 39.

The square root of 16509990 is about 4063.2487002397. The cubic root of 16509990 is about 254.6335374275.

The spelling of 16509990 in words is "sixteen million, five hundred nine thousand, nine hundred ninety".