21122775 has 84 divisors (see below), whose sum is σ = 42014920. Its totient is φ = 10497600.

The previous prime is 21122743. The next prime is 21122821. The reversal of 21122775 is 57722112.

It is not a de Polignac number, because 21122775 - 2⁵ = 21122743 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

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 83 ways as a sum of consecutive naturals, for example, 346245 + ... + 346305.

Almost surely, 2^21122775 is an apocalyptic number.

21122775 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21122775 is a deficient number, since it is larger than the sum of its proper divisors (20892145).

21122775 is an equidigital number, since it uses as much as digits as its factorization.

21122775 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 108 (or 88 counting only the distinct ones).

The product of its digits is 1960, while the sum is 27.

The square root of 21122775 is about 4595.9520232483. The cubic root of 21122775 is about 276.4290349988.

Adding to 21122775 its reverse (57722112), we get a palindrome (78844887).

The spelling of 21122775 in words is "twenty-one million, one hundred twenty-two thousand, seven hundred seventy-five".