16513221 has 4 divisors (see below), whose sum is σ = 22017632. Its totient is φ = 11008812.

The previous prime is 16513213. The next prime is 16513229. The reversal of 16513221 is 12231561.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is an interprime number because it is at equal distance from previous prime (16513213) and next prime (16513229).

It is not a de Polignac number, because 16513221 - 2³ = 16513213 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 (16513229) 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, 2752201 + ... + 2752206.

It is an arithmetic number, because the mean of its divisors is an integer number (5504408).

Almost surely, 2^16513221 is an apocalyptic number.

It is an amenable number.

16513221 is a deficient number, since it is larger than the sum of its proper divisors (5504411).

16513221 is an equidigital number, since it uses as much as digits as its factorization.

16513221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5504410.

The product of its digits is 360, while the sum is 21.

The square root of 16513221 is about 4063.6462690544. The cubic root of 16513221 is about 254.6501469126.

Adding to 16513221 its reverse (12231561), we get a palindrome (28744782).

The spelling of 16513221 in words is "sixteen million, five hundred thirteen thousand, two hundred twenty-one".