21321007 has 4 divisors (see below), whose sum is σ = 21682440. Its totient is φ = 20959576.

The previous prime is 21320987. The next prime is 21321019. The reversal of 21321007 is 70012312.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 21321007 - 2⁷ = 21320879 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21321067) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 180628 + ... + 180745.

It is an arithmetic number, because the mean of its divisors is an integer number (5420610).

Almost surely, 2^21321007 is an apocalyptic number.

21321007 is a deficient number, since it is larger than the sum of its proper divisors (361433).

21321007 is an equidigital number, since it uses as much as digits as its factorization.

21321007 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 361432.

The product of its (nonzero) digits is 84, while the sum is 16.

The square root of 21321007 is about 4617.4675959881. The cubic root of 21321007 is about 277.2910831854.

Adding to 21321007 its reverse (70012312), we get a palindrome (91333319).

The spelling of 21321007 in words is "twenty-one million, three hundred twenty-one thousand, seven".