4001531221 has 4 divisors (see below), whose sum is σ = 4041150444. Its totient is φ = 3961912000.

The previous prime is 4001531207. The next prime is 4001531227. The reversal of 4001531221 is 1221351004.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 3922516900 + 79014321 = 62630^2 + 8889^2 .

It is a cyclic number.

It is not a de Polignac number, because 4001531221 - 2⁵ = 4001531189 is a prime.

It is a super-2 number, since 2×4001531221² = 32024504225275501682, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (4001531227) 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, 19809460 + ... + 19809661.

It is an arithmetic number, because the mean of its divisors is an integer number (1010287611).

Almost surely, 2^4001531221 is an apocalyptic number.

It is an amenable number.

4001531221 is a deficient number, since it is larger than the sum of its proper divisors (39619223).

4001531221 is a wasteful number, since it uses less digits than its factorization.

4001531221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39619222.

The product of its (nonzero) digits is 240, while the sum is 19.

The square root of 4001531221 is about 63257.6574099927. The cubic root of 4001531221 is about 1587.6035812795.

Adding to 4001531221 its reverse (1221351004), we get a palindrome (5222882225).

The spelling of 4001531221 in words is "four billion, one million, five hundred thirty-one thousand, two hundred twenty-one".