3978639 has 24 divisors (see below), whose sum is σ = 6814080. Its totient is φ = 2272536.

The previous prime is 3978593. The next prime is 3978641. The reversal of 3978639 is 9368793.

It is a happy number.

3978639 is a `hidden beast` number, since 3 + 9 + 7 + 8 + 639 = 666.

It is not a de Polignac number, because 3978639 - 2⁷ = 3978511 is a prime.

It is a d-powerful number, because it can be written as 3⁵ + 9² + 7³ + 8⁷ + 6⁷ + 3¹³ + 9⁴ .

It is a junction number, because it is equal to n+sod(n) for n = 3978594 and 3978603.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (3978659) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 532 + ... + 2870.

It is an arithmetic number, because the mean of its divisors is an integer number (283920).

Almost surely, 2^3978639 is an apocalyptic number.

3978639 is a deficient number, since it is larger than the sum of its proper divisors (2835441).

3978639 is an equidigital number, since it uses as much as digits as its factorization.

3978639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2361 (or 2349 counting only the distinct ones).

The product of its digits is 244944, while the sum is 45.

The square root of 3978639 is about 1994.6526013319. The cubic root of 3978639 is about 158.4570300843.

The spelling of 3978639 in words is "three million, nine hundred seventy-eight thousand, six hundred thirty-nine".