16505021 has 8 divisors (see below), whose sum is σ = 17854200. Its totient is φ = 15167232.

The previous prime is 16505017. The next prime is 16505023. The reversal of 16505021 is 12050561.

It can be written as a sum of positive squares in 4 ways, for example, as 592900 + 15912121 = 770^2 + 3989^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 16505021 - 2² = 16505017 is a prime.

It is a super-3 number, since 3×16505021³ (a number of 23 digits) contains 333 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 16504984 and 16505002.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16505023) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 305 + ... + 5753.

It is an arithmetic number, because the mean of its divisors is an integer number (2231775).

Almost surely, 2^16505021 is an apocalyptic number.

It is an amenable number.

16505021 is a deficient number, since it is larger than the sum of its proper divisors (1349179).

16505021 is a wasteful number, since it uses less digits than its factorization.

16505021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5695.

The product of its (nonzero) digits is 300, while the sum is 20.

The square root of 16505021 is about 4062.6371976833. The cubic root of 16505021 is about 254.6079892392.

Adding to 16505021 its reverse (12050561), we get a palindrome (28555582).

The spelling of 16505021 in words is "sixteen million, five hundred five thousand, twenty-one".