16691491 has 8 divisors (see below), whose sum is σ = 17704224. Its totient is φ = 15702720.

The previous prime is 16691471. The next prime is 16691503. The reversal of 16691491 is 19419661.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 16691491 - 2¹¹ = 16689443 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 16691491.

It is not an unprimeable number, because it can be changed into a prime (16691401) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4546 + ... + 7351.

It is an arithmetic number, because the mean of its divisors is an integer number (2213028).

Almost surely, 2^16691491 is an apocalyptic number.

16691491 is a deficient number, since it is larger than the sum of its proper divisors (1012733).

16691491 is a wasteful number, since it uses less digits than its factorization.

16691491 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11981.

The product of its digits is 11664, while the sum is 37.

The square root of 16691491 is about 4085.5221208555. The cubic root of 16691491 is about 255.5632353570.

It can be divided in two parts, 1669 and 1491, that added together give a triangular number (3160 = T₇₉).

The spelling of 16691491 in words is "sixteen million, six hundred ninety-one thousand, four hundred ninety-one".