16221845 has 4 divisors (see below), whose sum is σ = 19466220. Its totient is φ = 12977472.

The previous prime is 16221833. The next prime is 16221857. The reversal of 16221845 is 54812261.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 54812261 = 7 ⋅7830323.

It is an interprime number because it is at equal distance from previous prime (16221833) and next prime (16221857).

It can be written as a sum of positive squares in 2 ways, for example, as 3845521 + 12376324 = 1961^2 + 3518^2 .

It is a cyclic number.

It is not a de Polignac number, because 16221845 - 2⁸ = 16221589 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1622180 + ... + 1622189.

It is an arithmetic number, because the mean of its divisors is an integer number (4866555).

Almost surely, 2^16221845 is an apocalyptic number.

It is an amenable number.

16221845 is a deficient number, since it is larger than the sum of its proper divisors (3244375).

16221845 is an equidigital number, since it uses as much as digits as its factorization.

16221845 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3244374.

The product of its digits is 3840, while the sum is 29.

The square root of 16221845 is about 4027.6351622261. The cubic root of 16221845 is about 253.1434817578.

The spelling of 16221845 in words is "sixteen million, two hundred twenty-one thousand, eight hundred forty-five".