16691640 has 128 divisors (see below), whose sum is σ = 59166720. Its totient is φ = 3686400.

The previous prime is 16691621. The next prime is 16691651. The reversal of 16691640 is 4619661.

16691640 is nontrivially palindromic in base 11.

It is a super-2 number, since 2×16691640² = 557221691779200, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 25720 + ... + 26360.

It is an arithmetic number, because the mean of its divisors is an integer number (462240).

Almost surely, 2^16691640 is an apocalyptic number.

16691640 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 16691640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29583360).

16691640 is an abundant number, since it is smaller than the sum of its proper divisors (42475080).

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

16691640 is a wasteful number, since it uses less digits than its factorization.

16691640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 693 (or 689 counting only the distinct ones).

The product of its (nonzero) digits is 7776, while the sum is 33.

The square root of 16691640 is about 4085.5403559382. The cubic root of 16691640 is about 255.5639958005.

It can be divided in two parts, 166 and 91640, that added together give a triangular number (91806 = T₄₂₈).

The spelling of 16691640 in words is "sixteen million, six hundred ninety-one thousand, six hundred forty".