16187221 has 8 divisors (see below), whose sum is σ = 17436320. Its totient is φ = 14977872.

The previous prime is 16187201. The next prime is 16187273. The reversal of 16187221 is 12278161.

16187221 = 914² + 915² + ... + 932².

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 16187221 - 2¹³ = 16179029 is a prime.

It is a super-2 number, since 2×16187221² = 524052247405682, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 16187221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16187201) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9090 + ... + 10723.

It is an arithmetic number, because the mean of its divisors is an integer number (2179540).

Almost surely, 2^16187221 is an apocalyptic number.

It is an amenable number.

16187221 is a deficient number, since it is larger than the sum of its proper divisors (1249099).

16187221 is a wasteful number, since it uses less digits than its factorization.

16187221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19875.

The product of its digits is 1344, while the sum is 28.

The square root of 16187221 is about 4023.3345622754. The cubic root of 16187221 is about 252.9632498293.

The spelling of 16187221 in words is "sixteen million, one hundred eighty-seven thousand, two hundred twenty-one".