21201321 has 16 divisors (see below), whose sum is σ = 29859840. Its totient is φ = 13343760.

The previous prime is 21201311. The next prime is 21201347. The reversal of 21201321 is 12310212.

It is not a de Polignac number, because 21201321 - 2⁵ = 21201289 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21201297 and 21201306.

It is not an unprimeable number, because it can be changed into a prime (21201311) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 24136 + ... + 24998.

It is an arithmetic number, because the mean of its divisors is an integer number (1866240).

Almost surely, 2^21201321 is an apocalyptic number.

It is an amenable number.

21201321 is a deficient number, since it is larger than the sum of its proper divisors (8658519).

21201321 is a wasteful number, since it uses less digits than its factorization.

21201321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1316.

The product of its (nonzero) digits is 24, while the sum is 12.

The square root of 21201321 is about 4604.4892224871. The cubic root of 21201321 is about 276.7712491508.

Adding to 21201321 its reverse (12310212), we get a palindrome (33511533).

The spelling of 21201321 in words is "twenty-one million, two hundred one thousand, three hundred twenty-one".