16728167821 has 4 divisors (see below), whose sum is σ = 16731370944. Its totient is φ = 16724964700.

The previous prime is 16728167803. The next prime is 16728167843. The reversal of 16728167821 is 12876182761.

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, and also an emirpimes, since its reverse is a distinct semiprime: 12876182761 = 13 ⋅990475597.

It is a cyclic number.

It is not a de Polignac number, because 16728167821 - 2¹³ = 16728159629 is a prime.

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16728167801) 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, 1593715 + ... + 1604176.

It is an arithmetic number, because the mean of its divisors is an integer number (4182842736).

Almost surely, 2^16728167821 is an apocalyptic number.

It is an amenable number.

16728167821 is a deficient number, since it is larger than the sum of its proper divisors (3203123).

16728167821 is an equidigital number, since it uses as much as digits as its factorization.

16728167821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3203122.

The product of its digits is 451584, while the sum is 49.

The spelling of 16728167821 in words is "sixteen billion, seven hundred twenty-eight million, one hundred sixty-seven thousand, eight hundred twenty-one".