21321011 has 4 divisors (see below), whose sum is σ = 21330672. Its totient is φ = 21311352.

The previous prime is 21320987. The next prime is 21321019. The reversal of 21321011 is 11012312.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21321011 - 2⁶ = 21320947 is a prime.

It is a Duffinian number.

It is a plaindrome in base 13.

It is a junction number, because it is equal to n+sod(n) for n = 21320983 and 21321001.

It is not an unprimeable number, because it can be changed into a prime (21321019) 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, 290 + ... + 6536.

It is an arithmetic number, because the mean of its divisors is an integer number (5332668).

Almost surely, 2^21321011 is an apocalyptic number.

21321011 is a deficient number, since it is larger than the sum of its proper divisors (9661).

21321011 is an equidigital number, since it uses as much as digits as its factorization.

21321011 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9660.

The product of its (nonzero) digits is 12, while the sum is 11.

The square root of 21321011 is about 4617.4680291259. The cubic root of 21321011 is about 277.2911005261.

Adding to 21321011 its reverse (11012312), we get a palindrome (32333323).

The spelling of 21321011 in words is "twenty-one million, three hundred twenty-one thousand, eleven".