21245775 has 12 divisors (see below), whose sum is σ = 35126472. Its totient is φ = 11331040.

The previous prime is 21245773. The next prime is 21245779. The reversal of 21245775 is 57754212.

It is not a de Polignac number, because 21245775 - 2¹ = 21245773 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21245771) 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 11 ways as a sum of consecutive naturals, for example, 141564 + ... + 141713.

It is an arithmetic number, because the mean of its divisors is an integer number (2927206).

Almost surely, 2^21245775 is an apocalyptic number.

21245775 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21245775 is a deficient number, since it is larger than the sum of its proper divisors (13880697).

21245775 is a wasteful number, since it uses less digits than its factorization.

21245775 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 283290 (or 283285 counting only the distinct ones).

The product of its digits is 19600, while the sum is 33.

The square root of 21245775 is about 4609.3139402735. The cubic root of 21245775 is about 276.9645547142.

Adding to 21245775 its reverse (57754212), we get a palindrome (78999987).

The spelling of 21245775 in words is "twenty-one million, two hundred forty-five thousand, seven hundred seventy-five".