16421504 has 64 divisors (see below), whose sum is σ = 36352800. Its totient is φ = 7326720.

The previous prime is 16421501. The next prime is 16421513. The reversal of 16421504 is 40512461.

It is a tau number, because it is divible by the number of its divisors (64).

It is a self number, because there is not a number n which added to its sum of digits gives 16421504.

It is not an unprimeable number, because it can be changed into a prime (16421501) 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, 150602 + ... + 150710.

Almost surely, 2^16421504 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 16421504, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (18176400).

16421504 is an abundant number, since it is smaller than the sum of its proper divisors (19931296).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

16421504 is a wasteful number, since it uses less digits than its factorization.

16421504 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 241 (or 229 counting only the distinct ones).

The product of its (nonzero) digits is 960, while the sum is 23.

The square root of 16421504 is about 4052.3454936617. The cubic root of 16421504 is about 254.1778158446.

Adding to 16421504 its reverse (40512461), we get a palindrome (56933965).

The spelling of 16421504 in words is "sixteen million, four hundred twenty-one thousand, five hundred four".