39978 has 12 divisors (see below), whose sum is σ = 86658. Its totient is φ = 13320.

The previous prime is 39971. The next prime is 39979. The reversal of 39978 is 87993.

It can be written as a sum of positive squares in only one way, i.e., 31329 + 8649 = 177^2 + 93^2 .

It is not an unprimeable number, because it can be changed into a prime (39971) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1093 + ... + 1128.

2³⁹⁹⁷⁸ is an apocalyptic number.

39978 is an abundant number, since it is smaller than the sum of its proper divisors (46680).

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

39978 is a wasteful number, since it uses less digits than its factorization.

39978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2229 (or 2226 counting only the distinct ones).

The product of its digits is 13608, while the sum is 36.

The square root of 39978 is about 199.9449924354. The cubic root of 39978 is about 34.1932478719.

It can be divided in two parts, 3997 and 8, that added together give a triangular number (4005 = T₈₉).

The spelling of 39978 in words is "thirty-nine thousand, nine hundred seventy-eight".