12172021 has 4 divisors (see below), whose sum is σ = 12279852. Its totient is φ = 12064192.

The previous prime is 12172019. The next prime is 12172049. The reversal of 12172021 is 12027121.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12027121 = 107 ⋅112403.

It can be written as a sum of positive squares in 2 ways, for example, as 1347921 + 10824100 = 1161^2 + 3290^2 .

It is a cyclic number.

It is not a de Polignac number, because 12172021 - 2¹ = 12172019 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 12171986 and 12172004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (12172081) 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, 53746 + ... + 53971.

It is an arithmetic number, because the mean of its divisors is an integer number (3069963).

Almost surely, 2^12172021 is an apocalyptic number.

It is an amenable number.

12172021 is a deficient number, since it is larger than the sum of its proper divisors (107831).

12172021 is a wasteful number, since it uses less digits than its factorization.

12172021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 107830.

The product of its (nonzero) digits is 56, while the sum is 16.

The square root of 12172021 is about 3488.8423581469. The cubic root of 12172021 is about 230.0316339602.

Adding to 12172021 its reverse (12027121), we get a palindrome (24199142).

The spelling of 12172021 in words is "twelve million, one hundred seventy-two thousand, twenty-one".