3978 has 24 divisors (see below), whose sum is σ = 9828. Its totient is φ = 1152.

The previous prime is 3967. The next prime is 3989. The reversal of 3978 is 8793.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (3967) and next prime (3989).

It can be written as a sum of positive squares in 2 ways, for example, as 3969 + 9 = 63^2 + 3^2 .

It is a nialpdrome in base 9.

It is a congruent number.

It is an unprimeable number.

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 11 ways as a sum of consecutive naturals, for example, 226 + ... + 242.

2³⁹⁷⁸ is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 3978, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (4914).

3978 is an abundant number, since it is smaller than the sum of its proper divisors (5850).

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

3978 is a wasteful number, since it uses less digits than its factorization.

3978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38 (or 35 counting only the distinct ones).

The product of its digits is 1512, while the sum is 27.

The square root of 3978 is about 63.0713881249. The cubic root of 3978 is about 15.8448546491.

Adding to 3978 its sum of digits (27), we get a triangular number (4005 = T₈₉).

The spelling of 3978 in words is "three thousand, nine hundred seventy-eight".