16685025821 has 4 divisors (see below), whose sum is σ = 16685331072. Its totient is φ = 16684720572.

The previous prime is 16685025767. The next prime is 16685025829. The reversal of 16685025821 is 12852058661.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 16685025821 - 2¹⁸ = 16684763677 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16685025829) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 45635 + ... + 188288.

It is an arithmetic number, because the mean of its divisors is an integer number (4171332768).

Almost surely, 2^16685025821 is an apocalyptic number.

It is an amenable number.

16685025821 is a deficient number, since it is larger than the sum of its proper divisors (305251).

16685025821 is an equidigital number, since it uses as much as digits as its factorization.

16685025821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 305250.

The product of its (nonzero) digits is 230400, while the sum is 44.

The spelling of 16685025821 in words is "sixteen billion, six hundred eighty-five million, twenty-five thousand, eight hundred twenty-one".