16705021 has 4 divisors (see below), whose sum is σ = 16716700. Its totient is φ = 16693344.

The previous prime is 16704983. The next prime is 16705099. The reversal of 16705021 is 12050761.

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 14100025 + 2604996 = 3755^2 + 1614^2 .

It is a 3-Lehmer number, since φ(16705021) divides (16705021-1)³.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-16705021 is a prime.

It is a super-2 number, since 2×16705021² = 558115453220882, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 16704983 and 16705001.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16705721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3336 + ... + 6673.

It is an arithmetic number, because the mean of its divisors is an integer number (4179175).

It is a Poulet number, since it divides 2^16705020-1.

Almost surely, 2^16705021 is an apocalyptic number.

It is an amenable number.

16705021 is a deficient number, since it is larger than the sum of its proper divisors (11679).

16705021 is a wasteful number, since it uses less digits than its factorization.

16705021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11678.

The product of its (nonzero) digits is 420, while the sum is 22.

The square root of 16705021 is about 4087.1776325479. The cubic root of 16705021 is about 255.6322692680.

Adding to 16705021 its reverse (12050761), we get a palindrome (28755782).

The spelling of 16705021 in words is "sixteen million, seven hundred five thousand, twenty-one".