21423916821 has 8 divisors (see below), whose sum is σ = 29486681344. Its totient is φ = 13821881760.

The previous prime is 21423916793. The next prime is 21423916903. The reversal of 21423916821 is 12861932412.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21423916821 - 2¹³ = 21423908629 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21423916821.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21423916021) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 115182256 + ... + 115182441.

It is an arithmetic number, because the mean of its divisors is an integer number (3685835168).

Almost surely, 2^21423916821 is an apocalyptic number.

It is an amenable number.

21423916821 is a deficient number, since it is larger than the sum of its proper divisors (8062764523).

21423916821 is a wasteful number, since it uses less digits than its factorization.

21423916821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 230364731.

The product of its digits is 41472, while the sum is 39.

The spelling of 21423916821 in words is "twenty-one billion, four hundred twenty-three million, nine hundred sixteen thousand, eight hundred twenty-one".