21346321521 has 8 divisors (see below), whose sum is σ = 32527728064. Its totient is φ = 12197898000.

The previous prime is 21346321429. The next prime is 21346321531. The reversal of 21346321521 is 12512364312.

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

It is not a de Polignac number, because 21346321521 - 2¹¹ = 21346319473 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21346321531) 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, 508245730 + ... + 508245771.

It is an arithmetic number, because the mean of its divisors is an integer number (4065966008).

Almost surely, 2^21346321521 is an apocalyptic number.

21346321521 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21346321521 is a deficient number, since it is larger than the sum of its proper divisors (11181406543).

21346321521 is a wasteful number, since it uses less digits than its factorization.

21346321521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1016491511.

The product of its digits is 8640, while the sum is 30.

Adding to 21346321521 its reverse (12512364312), we get a palindrome (33858685833).

The spelling of 21346321521 in words is "twenty-one billion, three hundred forty-six million, three hundred twenty-one thousand, five hundred twenty-one".