3721821 has 4 divisors (see below), whose sum is σ = 4962432. Its totient is φ = 2481212.

The previous prime is 3721813. The next prime is 3721847. The reversal of 3721821 is 1281273.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 3721821 - 2³ = 3721813 is a prime.

It is a D-number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 3721791 and 3721800.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (3721811) 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, 620301 + ... + 620306.

It is an arithmetic number, because the mean of its divisors is an integer number (1240608).

Almost surely, 2^3721821 is an apocalyptic number.

It is an amenable number.

3721821 is a deficient number, since it is larger than the sum of its proper divisors (1240611).

3721821 is a wasteful number, since it uses less digits than its factorization.

3721821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1240610.

The product of its digits is 672, while the sum is 24.

The square root of 3721821 is about 1929.2021667000. The cubic root of 3721821 is about 154.9714966665.

The spelling of 3721821 in words is "three million, seven hundred twenty-one thousand, eight hundred twenty-one".