21479096921 has 4 divisors (see below), whose sum is σ = 22059613092. Its totient is φ = 20898580752.

The previous prime is 21479096897. The next prime is 21479096971. The reversal of 21479096921 is 12969097412.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 15968113225 + 5510983696 = 126365^2 + 74236^2 .

It is a cyclic number.

It is not a de Polignac number, because 21479096921 - 2¹⁸ = 21478834777 is a prime.

It is a super-2 number, since 2×21479096921² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21479096921.

It is not an unprimeable number, because it can be changed into a prime (21479096971) 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, 290258030 + ... + 290258103.

It is an arithmetic number, because the mean of its divisors is an integer number (5514903273).

Almost surely, 2^21479096921 is an apocalyptic number.

It is an amenable number.

21479096921 is a deficient number, since it is larger than the sum of its proper divisors (580516171).

21479096921 is an equidigital number, since it uses as much as digits as its factorization.

21479096921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 580516170.

The product of its (nonzero) digits is 489888, while the sum is 50.

The spelling of 21479096921 in words is "twenty-one billion, four hundred seventy-nine million, ninety-six thousand, nine hundred twenty-one".