21032321 has 4 divisors (see below), whose sum is σ = 21150000. Its totient is φ = 20914644.

The previous prime is 21032309. The next prime is 21032329. The reversal of 21032321 is 12323012.

It is a happy number.

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 a de Polignac number, because none of the positive numbers 2^k-21032321 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21032296 and 21032305.

It is not an unprimeable number, because it can be changed into a prime (21032329) 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, 58571 + ... + 58928.

It is an arithmetic number, because the mean of its divisors is an integer number (5287500).

Almost surely, 2^21032321 is an apocalyptic number.

It is an amenable number.

21032321 is a deficient number, since it is larger than the sum of its proper divisors (117679).

21032321 is a wasteful number, since it uses less digits than its factorization.

21032321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 117678.

The product of its (nonzero) digits is 72, while the sum is 14.

The square root of 21032321 is about 4586.1008493054. The cubic root of 21032321 is about 276.0338866536.

Adding to 21032321 its reverse (12323012), we get a palindrome (33355333).

The spelling of 21032321 in words is "twenty-one million, thirty-two thousand, three hundred twenty-one".