3972421 has 4 divisors (see below), whose sum is σ = 3977932. Its totient is φ = 3966912.

The previous prime is 3972413. The next prime is 3972427. The reversal of 3972421 is 1242793.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1242793 = 37 ⋅33589.

It can be written as a sum of positive squares in 2 ways, for example, as 343396 + 3629025 = 586^2 + 1905^2 .

It is a cyclic number.

It is not a de Polignac number, because 3972421 - 2³ = 3972413 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 3972421.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (3972427) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1476 + ... + 3181.

It is an arithmetic number, because the mean of its divisors is an integer number (994483).

Almost surely, 2^3972421 is an apocalyptic number.

It is an amenable number.

3972421 is a deficient number, since it is larger than the sum of its proper divisors (5511).

3972421 is an equidigital number, since it uses as much as digits as its factorization.

3972421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5510.

The product of its digits is 3024, while the sum is 28.

The square root of 3972421 is about 1993.0933244582. The cubic root of 3972421 is about 158.3744390658.

The spelling of 3972421 in words is "three million, nine hundred seventy-two thousand, four hundred twenty-one".