16991220 has 48 divisors (see below), whose sum is σ = 48742848. Its totient is φ = 4419840.

The previous prime is 16991213. The next prime is 16991237. The reversal of 16991220 is 2219961.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 994 + ... + 5913.

It is an arithmetic number, because the mean of its divisors is an integer number (1015476).

Almost surely, 2^16991220 is an apocalyptic number.

16991220 is a gapful number since it is divisible by the number (10) 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 16991220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24371424).

16991220 is an abundant number, since it is smaller than the sum of its proper divisors (31751628).

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

16991220 is a wasteful number, since it uses less digits than its factorization.

16991220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6960 (or 6958 counting only the distinct ones).

The product of its (nonzero) digits is 1944, while the sum is 30.

The square root of 16991220 is about 4122.0407567126. The cubic root of 16991220 is about 257.0838850657.

The spelling of 16991220 in words is "sixteen million, nine hundred ninety-one thousand, two hundred twenty".