15978 has 8 divisors (see below), whose sum is σ = 31968. Its totient is φ = 5324.

The previous prime is 15973. The next prime is 15991. The reversal of 15978 is 87951.

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

15978 is an admirable number.

It is a Curzon number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 15978.

It is not an unprimeable number, because it can be changed into a prime (15971) by changing a digit.

15978 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1326 + ... + 1337.

It is an arithmetic number, because the mean of its divisors is an integer number (3996).

2¹⁵⁹⁷⁸ is an apocalyptic number.

15978 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

It is a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (15984).

15978 is a wasteful number, since it uses less digits than its factorization.

15978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2668.

The product of its digits is 2520, while the sum is 30.

The square root of 15978 is about 126.4041138571. The cubic root of 15978 is about 25.1868664241.

The spelling of 15978 in words is "fifteen thousand, nine hundred seventy-eight".