13439978 has 4 divisors (see below), whose sum is σ = 20159970. Its totient is φ = 6719988.

The previous prime is 13439939. The next prime is 13440001. The reversal of 13439978 is 87993431.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 87993431 = 163 ⋅539837.

It can be written as a sum of positive squares in only one way, i.e., 9467929 + 3972049 = 3077^2 + 1993^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3359993 + ... + 3359996.

Almost surely, 2^13439978 is an apocalyptic number.

13439978 is a deficient number, since it is larger than the sum of its proper divisors (6719992).

13439978 is an equidigital number, since it uses as much as digits as its factorization.

13439978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6719991.

The product of its digits is 163296, while the sum is 44.

The square root of 13439978 is about 3666.0575554675. The cubic root of 13439978 is about 237.7567483820.

The spelling of 13439978 in words is "thirteen million, four hundred thirty-nine thousand, nine hundred seventy-eight".