16823989421 has 4 divisors (see below), whose sum is σ = 17013023100. Its totient is φ = 16634955744.

The previous prime is 16823989393. The next prime is 16823989459. The reversal of 16823989421 is 12498932861.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12498932861 = 41 ⋅304852021.

It can be written as a sum of positive squares in 2 ways, for example, as 9958044100 + 6865945321 = 99790^2 + 82861^2 .

It is a cyclic number.

It is not a de Polignac number, because 16823989421 - 2¹⁰ = 16823988397 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16823989471) 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, 94516706 + ... + 94516883.

It is an arithmetic number, because the mean of its divisors is an integer number (4253255775).

Almost surely, 2^16823989421 is an apocalyptic number.

It is an amenable number.

16823989421 is a deficient number, since it is larger than the sum of its proper divisors (189033679).

16823989421 is an equidigital number, since it uses as much as digits as its factorization.

16823989421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 189033678.

The product of its digits is 1492992, while the sum is 53.

The spelling of 16823989421 in words is "sixteen billion, eight hundred twenty-three million, nine hundred eighty-nine thousand, four hundred twenty-one".