3931021 has 4 divisors (see below), whose sum is σ = 3970044. Its totient is φ = 3892000.

The previous prime is 3931001. The next prime is 3931027. The reversal of 3931021 is 1201393.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1201393 = 311 ⋅3863.

It can be written as a sum of positive squares in 2 ways, for example, as 1590121 + 2340900 = 1261^2 + 1530^2 .

It is a cyclic number.

It is not a de Polignac number, because 3931021 - 2⁵ = 3930989 is a prime.

It is a super-2 number, since 2×3931021² = 30905852204882, which contains 22 as substring.

It is a Duffinian number.

3931021 is a lucky number.

It is a self number, because there is not a number n which added to its sum of digits gives 3931021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (3931027) 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, 19360 + ... + 19561.

It is an arithmetic number, because the mean of its divisors is an integer number (992511).

Almost surely, 2^3931021 is an apocalyptic number.

It is an amenable number.

3931021 is a deficient number, since it is larger than the sum of its proper divisors (39023).

3931021 is a wasteful number, since it uses less digits than its factorization.

3931021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39022.

The product of its (nonzero) digits is 162, while the sum is 19.

The square root of 3931021 is about 1982.6802566223. The cubic root of 3931021 is about 157.8223314007.

The spelling of 3931021 in words is "three million, nine hundred thirty-one thousand, twenty-one".