21083584921 has 4 divisors (see below), whose sum is σ = 24095525632. Its totient is φ = 18071644212.

The previous prime is 21083584813. The next prime is 21083584927. The reversal of 21083584921 is 12948538012.

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.

It is a cyclic number.

It is not a de Polignac number, because 21083584921 - 2¹⁹ = 21083060633 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21083584927) 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, 1505970345 + ... + 1505970358.

It is an arithmetic number, because the mean of its divisors is an integer number (6023881408).

Almost surely, 2^21083584921 is an apocalyptic number.

It is an amenable number.

21083584921 is a deficient number, since it is larger than the sum of its proper divisors (3011940711).

21083584921 is an equidigital number, since it uses as much as digits as its factorization.

21083584921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3011940710.

The product of its (nonzero) digits is 138240, while the sum is 43.

The spelling of 21083584921 in words is "twenty-one billion, eighty-three million, five hundred eighty-four thousand, nine hundred twenty-one".