3972147221 has 12 divisors (see below), whose sum is σ = 4621690188. Its totient is φ = 3403939392.

The previous prime is 3972147217. The next prime is 3972147233. The reversal of 3972147221 is 1227412793.

It can be written as a sum of positive squares in 2 ways, for example, as 1572519025 + 2399628196 = 39655^2 + 48986^2 .

It is not a de Polignac number, because 3972147221 - 2² = 3972147217 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (3972147721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 405635 + ... + 415311.

It is an arithmetic number, because the mean of its divisors is an integer number (385140849).

Almost surely, 2^3972147221 is an apocalyptic number.

It is an amenable number.

3972147221 is a deficient number, since it is larger than the sum of its proper divisors (649542967).

3972147221 is an equidigital number, since it uses as much as digits as its factorization.

3972147221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18068 (or 18061 counting only the distinct ones).

The product of its digits is 42336, while the sum is 38.

The square root of 3972147221 is about 63024.9729948375. The cubic root of 3972147221 is about 1583.7080059681.

The spelling of 3972147221 in words is "three billion, nine hundred seventy-two million, one hundred forty-seven thousand, two hundred twenty-one".