16618621 has 4 divisors (see below), whose sum is σ = 16678044. Its totient is φ = 16559200.

The previous prime is 16618603. The next prime is 16618631. The reversal of 16618621 is 12681661.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 10791225 + 5827396 = 3285^2 + 2414^2 .

It is a cyclic number.

It is not a de Polignac number, because 16618621 - 2¹¹ = 16616573 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16618601) 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, 29290 + ... + 29851.

It is an arithmetic number, because the mean of its divisors is an integer number (4169511).

Almost surely, 2^16618621 is an apocalyptic number.

It is an amenable number.

16618621 is a deficient number, since it is larger than the sum of its proper divisors (59423).

16618621 is an equidigital number, since it uses as much as digits as its factorization.

16618621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 59422.

The product of its digits is 3456, while the sum is 31.

The square root of 16618621 is about 4076.5942893548. The cubic root of 16618621 is about 255.1907889106.

The spelling of 16618621 in words is "sixteen million, six hundred eighteen thousand, six hundred twenty-one".