16215023221 has 4 divisors (see below), whose sum is σ = 16217390700. Its totient is φ = 16212655744.

The previous prime is 16215023203. The next prime is 16215023243. The reversal of 16215023221 is 12232051261.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12232051261 = 75479 ⋅162059.

It can be written as a sum of positive squares in 2 ways, for example, as 928420900 + 15286602321 = 30470^2 + 123639^2 .

It is a cyclic number.

It is not a de Polignac number, because 16215023221 - 2²⁵ = 16181468789 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16215023021) 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, 1173436 + ... + 1187173.

It is an arithmetic number, because the mean of its divisors is an integer number (4054347675).

Almost surely, 2^16215023221 is an apocalyptic number.

It is an amenable number.

16215023221 is a deficient number, since it is larger than the sum of its proper divisors (2367479).

16215023221 is an equidigital number, since it uses as much as digits as its factorization.

16215023221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2367478.

The product of its (nonzero) digits is 1440, while the sum is 25.

Adding to 16215023221 its reverse (12232051261), we get a palindrome (28447074482).

The spelling of 16215023221 in words is "sixteen billion, two hundred fifteen million, twenty-three thousand, two hundred twenty-one".