21855375 has 24 divisors (see below), whose sum is σ = 39399984. Its totient is φ = 11655600.

The previous prime is 21855367. The next prime is 21855389. The reversal of 21855375 is 57355812.

It is not a de Polignac number, because 21855375 - 2³ = 21855367 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 8589 + ... + 10838.

It is an arithmetic number, because the mean of its divisors is an integer number (1641666).

Almost surely, 2^21855375 is an apocalyptic number.

21855375 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21855375 is a deficient number, since it is larger than the sum of its proper divisors (17544609).

21855375 is a wasteful number, since it uses less digits than its factorization.

21855375 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19448 (or 19435 counting only the distinct ones).

The product of its digits is 42000, while the sum is 36.

The square root of 21855375 is about 4674.9732619556. The cubic root of 21855375 is about 279.5885751808.

The spelling of 21855375 in words is "twenty-one million, eight hundred fifty-five thousand, three hundred seventy-five".