13993978 has 4 divisors (see below), whose sum is σ = 20990970. Its totient is φ = 6996988.

The previous prime is 13993951. The next prime is 13993999. The reversal of 13993978 is 87939931.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 87939931 = 6203 ⋅14177.

It can be written as a sum of positive squares in only one way, i.e., 8485569 + 5508409 = 2913^2 + 2347^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3498493 + ... + 3498496.

Almost surely, 2^13993978 is an apocalyptic number.

13993978 is a deficient number, since it is larger than the sum of its proper divisors (6996992).

13993978 is an equidigital number, since it uses as much as digits as its factorization.

13993978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6996991.

The product of its digits is 367416, while the sum is 49.

The square root of 13993978 is about 3740.8525766194. The cubic root of 13993978 is about 240.9796646122.

The spelling of 13993978 in words is "thirteen million, nine hundred ninety-three thousand, nine hundred seventy-eight".