21150321 has 4 divisors (see below), whose sum is σ = 28200432. Its totient is φ = 14100212.

The previous prime is 21150313. The next prime is 21150331. The reversal of 21150321 is 12305112.

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 21150321 - 2³ = 21150313 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21150321.

It is not an unprimeable number, because it can be changed into a prime (21150331) 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, 3525051 + ... + 3525056.

It is an arithmetic number, because the mean of its divisors is an integer number (7050108).

Almost surely, 2^21150321 is an apocalyptic number.

It is an amenable number.

21150321 is a deficient number, since it is larger than the sum of its proper divisors (7050111).

21150321 is an equidigital number, since it uses as much as digits as its factorization.

21150321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7050110.

The product of its (nonzero) digits is 60, while the sum is 15.

The square root of 21150321 is about 4598.9478144463. The cubic root of 21150321 is about 276.5491455839.

Adding to 21150321 its reverse (12305112), we get a palindrome (33455433).

The spelling of 21150321 in words is "twenty-one million, one hundred fifty thousand, three hundred twenty-one".