3721521 has 16 divisors (see below), whose sum is σ = 5379264. Its totient is φ = 2279424.

The previous prime is 3721489. The next prime is 3721537. The reversal of 3721521 is 1251273.

It is not a de Polignac number, because 3721521 - 2⁵ = 3721489 is a prime.

It is an Ulam number.

It is a Curzon number.

3721521 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (3721621) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1345 + ... + 3041.

It is an arithmetic number, because the mean of its divisors is an integer number (336204).

Almost surely, 2^3721521 is an apocalyptic number.

It is an amenable number.

3721521 is a deficient number, since it is larger than the sum of its proper divisors (1657743).

3721521 is a wasteful number, since it uses less digits than its factorization.

3721521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1760.

The product of its digits is 420, while the sum is 21.

The square root of 3721521 is about 1929.1244127842. The cubic root of 3721521 is about 154.9673326925.

Adding to 3721521 its reverse (1251273), we get a palindrome (4972794).

The spelling of 3721521 in words is "three million, seven hundred twenty-one thousand, five hundred twenty-one".