16421705 has 4 divisors (see below), whose sum is σ = 19706052. Its totient is φ = 13137360.

The previous prime is 16421693. The next prime is 16421707. The reversal of 16421705 is 50712461.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 50712461 = 2399 ⋅21139.

It can be written as a sum of positive squares in 2 ways, for example, as 9174841 + 7246864 = 3029^2 + 2692^2 .

It is a de Polignac number, because none of the positive numbers 2^k-16421705 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16421707) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1642166 + ... + 1642175.

It is an arithmetic number, because the mean of its divisors is an integer number (4926513).

Almost surely, 2^16421705 is an apocalyptic number.

It is an amenable number.

16421705 is a deficient number, since it is larger than the sum of its proper divisors (3284347).

16421705 is an equidigital number, since it uses as much as digits as its factorization.

16421705 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3284346.

The product of its (nonzero) digits is 1680, while the sum is 26.

The square root of 16421705 is about 4052.3702940378. The cubic root of 16421705 is about 254.1788528900.

The spelling of 16421705 in words is "sixteen million, four hundred twenty-one thousand, seven hundred five".