21011321 has 8 divisors (see below), whose sum is σ = 22204800. Its totient is φ = 19826640.

The previous prime is 21011317. The next prime is 21011327. The reversal of 21011321 is 12311012.

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

It is a cyclic number.

It is not a de Polignac number, because 21011321 - 2² = 21011317 is a prime.

It is a super-2 number, since 2×21011321² = 882951220330082, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21011327) 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, 3056 + ... + 7166.

It is an arithmetic number, because the mean of its divisors is an integer number (2775600).

Almost surely, 2^21011321 is an apocalyptic number.

It is an amenable number.

21011321 is a deficient number, since it is larger than the sum of its proper divisors (1193479).

21011321 is a wasteful number, since it uses less digits than its factorization.

21011321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4399.

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

The square root of 21011321 is about 4583.8107508928. The cubic root of 21011321 is about 275.9419861613.

Adding to 21011321 its reverse (12311012), we get a palindrome (33322333).

The spelling of 21011321 in words is "twenty-one million, eleven thousand, three hundred twenty-one".