21320575 has 12 divisors (see below), whose sum is σ = 26938008. Its totient is φ = 16733600.

The previous prime is 21320557. The next prime is 21320581. The reversal of 21320575 is 57502312.

It is not a de Polignac number, because 21320575 - 2⁵ = 21320543 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (25).

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 6721 + ... + 9370.

It is an arithmetic number, because the mean of its divisors is an integer number (2244834).

Almost surely, 2^21320575 is an apocalyptic number.

21320575 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21320575 is a deficient number, since it is larger than the sum of its proper divisors (5617433).

21320575 is a wasteful number, since it uses less digits than its factorization.

21320575 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16154 (or 16149 counting only the distinct ones).

The product of its (nonzero) digits is 2100, while the sum is 25.

The square root of 21320575 is about 4617.4208168630. The cubic root of 21320575 is about 277.2892103758.

Adding to 21320575 its reverse (57502312), we get a palindrome (78822887).

The spelling of 21320575 in words is "twenty-one million, three hundred twenty thousand, five hundred seventy-five".