21072375 has 24 divisors (see below), whose sum is σ = 37988496. Its totient is φ = 11238000.

The previous prime is 21072361. The next prime is 21072379. The reversal of 21072375 is 57327012.

It is not a de Polignac number, because 21072375 - 2⁹ = 21071863 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21072379) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 8241 + ... + 10490.

It is an arithmetic number, because the mean of its divisors is an integer number (1582854).

Almost surely, 2^21072375 is an apocalyptic number.

21072375 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21072375 is a deficient number, since it is larger than the sum of its proper divisors (16916121).

21072375 is a wasteful number, since it uses less digits than its factorization.

21072375 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18752 (or 18739 counting only the distinct ones).

The product of its (nonzero) digits is 2940, while the sum is 27.

The square root of 21072375 is about 4590.4656626534. The cubic root of 21072375 is about 276.2090020579.

Adding to 21072375 its reverse (57327012), we get a palindrome (78399387).

The spelling of 21072375 in words is "twenty-one million, seventy-two thousand, three hundred seventy-five".