3978621 has 6 divisors (see below), whose sum is σ = 5746910. Its totient is φ = 2652408.

The previous prime is 3978593. The next prime is 3978641. The reversal of 3978621 is 1268793.

It can be written as a sum of positive squares in only one way, i.e., 3956121 + 22500 = 1989^2 + 150^2 .

It is not a de Polignac number, because 3978621 - 2⁹ = 3978109 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (3978641) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 221026 + ... + 221043.

Almost surely, 2^3978621 is an apocalyptic number.

It is an amenable number.

3978621 is a deficient number, since it is larger than the sum of its proper divisors (1768289).

3978621 is a wasteful number, since it uses less digits than its factorization.

3978621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 442075 (or 442072 counting only the distinct ones).

The product of its digits is 18144, while the sum is 36.

The square root of 3978621 is about 1994.6480892629. The cubic root of 3978621 is about 158.4567911223.

The spelling of 3978621 in words is "three million, nine hundred seventy-eight thousand, six hundred twenty-one".