16918521 has 4 divisors (see below), whose sum is σ = 22558032. Its totient is φ = 11279012.

The previous prime is 16918511. The next prime is 16918619. The reversal of 16918521 is 12581961.

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 a cyclic number.

It is not a de Polignac number, because 16918521 - 2¹⁹ = 16394233 is a prime.

It is not an unprimeable number, because it can be changed into a prime (16918511) 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, 2819751 + ... + 2819756.

It is an arithmetic number, because the mean of its divisors is an integer number (5639508).

Almost surely, 2^16918521 is an apocalyptic number.

It is an amenable number.

16918521 is a deficient number, since it is larger than the sum of its proper divisors (5639511).

16918521 is an equidigital number, since it uses as much as digits as its factorization.

16918521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5639510.

The product of its digits is 4320, while the sum is 33.

The square root of 16918521 is about 4113.2129777098. The cubic root of 16918521 is about 256.7167060100.

The spelling of 16918521 in words is "sixteen million, nine hundred eighteen thousand, five hundred twenty-one".