16621331 has 4 divisors (see below), whose sum is σ = 16821672. Its totient is φ = 16420992.

The previous prime is 16621309. The next prime is 16621357. The reversal of 16621331 is 13312661.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 13312661 = 1811 ⋅7351.

It is a cyclic number.

It is not a de Polignac number, because 16621331 - 2¹⁴ = 16604947 is a prime.

It is a super-2 number, since 2×16621331² = 552537288423122, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 16621297 and 16621306.

It is not an unprimeable number, because it can be changed into a prime (16621361) 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, 100046 + ... + 100211.

It is an arithmetic number, because the mean of its divisors is an integer number (4205418).

Almost surely, 2^16621331 is an apocalyptic number.

16621331 is a deficient number, since it is larger than the sum of its proper divisors (200341).

16621331 is an equidigital number, since it uses as much as digits as its factorization.

16621331 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 200340.

The product of its digits is 648, while the sum is 23.

The square root of 16621331 is about 4076.9266611015. The cubic root of 16621331 is about 255.2046594849.

Adding to 16621331 its reverse (13312661), we get a palindrome (29933992).

It can be divided in two parts, 1662 and 1331, that multiplied together give a palindrome (2212122).

The spelling of 16621331 in words is "sixteen million, six hundred twenty-one thousand, three hundred thirty-one".