21321567 has 6 divisors (see below), whose sum is σ = 30797832. Its totient is φ = 14214372.

The previous prime is 21321563. The next prime is 21321577. The reversal of 21321567 is 76512312.

It is a happy number.

It is not a de Polignac number, because 21321567 - 2² = 21321563 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21321567.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21321563) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1184523 + ... + 1184540.

It is an arithmetic number, because the mean of its divisors is an integer number (5132972).

Almost surely, 2^21321567 is an apocalyptic number.

21321567 is a deficient number, since it is larger than the sum of its proper divisors (9476265).

21321567 is a wasteful number, since it uses less digits than its factorization.

21321567 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2369069 (or 2369066 counting only the distinct ones).

The product of its digits is 2520, while the sum is 27.

The square root of 21321567 is about 4617.5282348893. The cubic root of 21321567 is about 277.2935108638.

Adding to 21321567 its reverse (76512312), we get a palindrome (97833879).

The spelling of 21321567 in words is "twenty-one million, three hundred twenty-one thousand, five hundred sixty-seven".