16978391 has 8 divisors (see below), whose sum is σ = 17359920. Its totient is φ = 16599232.

The previous prime is 16978373. The next prime is 16978399. The reversal of 16978391 is 19387961.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-16978391 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16978399) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 29555 + ... + 30123.

It is an arithmetic number, because the mean of its divisors is an integer number (2169990).

Almost surely, 2^16978391 is an apocalyptic number.

16978391 is a deficient number, since it is larger than the sum of its proper divisors (381529).

16978391 is an equidigital number, since it uses as much as digits as its factorization.

16978391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1185.

The product of its digits is 81648, while the sum is 44.

The square root of 16978391 is about 4120.4843161939. The cubic root of 16978391 is about 257.0191661583.

The spelling of 16978391 in words is "sixteen million, nine hundred seventy-eight thousand, three hundred ninety-one".