21152321 has 2 divisors, whose sum is σ = 21152322. Its totient is φ = 21152320.

The previous prime is 21152317. The next prime is 21152333. The reversal of 21152321 is 12325112.

It is a happy number.

21152321 is nontrivially palindromic in base 16.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15295921 + 5856400 = 3911^2 + 2420^2 .

It is a cyclic number.

It is not a de Polignac number, because 21152321 - 2² = 21152317 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21152321.

It is not a weakly prime, because it can be changed into another prime (21152311) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10576160 + 10576161.

It is an arithmetic number, because the mean of its divisors is an integer number (10576161).

Almost surely, 2^21152321 is an apocalyptic number.

It is an amenable number.

21152321 is a deficient number, since it is larger than the sum of its proper divisors (1).

21152321 is an equidigital number, since it uses as much as digits as its factorization.

21152321 is an evil number, because the sum of its binary digits is even.

The product of its digits is 120, while the sum is 17.

The square root of 21152321 is about 4599.1652503471. The cubic root of 21152321 is about 276.5578622500.

Adding to 21152321 its reverse (12325112), we get a palindrome (33477433).

The spelling of 21152321 in words is "twenty-one million, one hundred fifty-two thousand, three hundred twenty-one".