16505421 has 16 divisors (see below), whose sum is σ = 23502336. Its totient is φ = 10278576.

The previous prime is 16505417. The next prime is 16505431. The reversal of 16505421 is 12450561.

It is not a de Polignac number, because 16505421 - 2² = 16505417 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 16505391 and 16505400.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16505431) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 186 + ... + 5748.

It is an arithmetic number, because the mean of its divisors is an integer number (1468896).

Almost surely, 2^16505421 is an apocalyptic number.

It is an amenable number.

16505421 is a deficient number, since it is larger than the sum of its proper divisors (6996915).

16505421 is a wasteful number, since it uses less digits than its factorization.

16505421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5632.

The product of its (nonzero) digits is 1200, while the sum is 24.

The square root of 16505421 is about 4062.6864264917. The cubic root of 16505421 is about 254.6100460349.

Adding to 16505421 its reverse (12450561), we get a palindrome (28955982).

The spelling of 16505421 in words is "sixteen million, five hundred five thousand, four hundred twenty-one".