21321535 has 4 divisors (see below), whose sum is σ = 25585848. Its totient is φ = 17057224.

The previous prime is 21321527. The next prime is 21321539. The reversal of 21321535 is 53512312.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21321535 - 2³ = 21321527 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21321539) 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, 2132149 + ... + 2132158.

It is an arithmetic number, because the mean of its divisors is an integer number (6396462).

Almost surely, 2^21321535 is an apocalyptic number.

21321535 is a deficient number, since it is larger than the sum of its proper divisors (4264313).

21321535 is an equidigital number, since it uses as much as digits as its factorization.

21321535 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4264312.

The product of its digits is 900, while the sum is 22.

The square root of 21321535 is about 4617.5247698307. The cubic root of 21321535 is about 277.2933721405.

Adding to 21321535 its reverse (53512312), we get a palindrome (74833847).

The spelling of 21321535 in words is "twenty-one million, three hundred twenty-one thousand, five hundred thirty-five".