21750105 has 16 divisors (see below), whose sum is σ = 37477440. Its totient is φ = 10707648.

The previous prime is 21750101. The next prime is 21750107. The reversal of 21750105 is 50105712.

It is not a de Polignac number, because 21750105 - 2² = 21750101 is a prime.

It is a super-2 number, since 2×21750105² = 946134135022050, which contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21750101) 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 15 ways as a sum of consecutive naturals, for example, 55575 + ... + 55964.

It is an arithmetic number, because the mean of its divisors is an integer number (2342340).

Almost surely, 2^21750105 is an apocalyptic number.

It is an amenable number.

21750105 is a deficient number, since it is larger than the sum of its proper divisors (15727335).

21750105 is a wasteful number, since it uses less digits than its factorization.

21750105 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 111560.

The product of its (nonzero) digits is 350, while the sum is 21.

The square root of 21750105 is about 4663.7007837124. The cubic root of 21750105 is about 279.1389577706.

Adding to 21750105 its reverse (50105712), we get a palindrome (71855817).

The spelling of 21750105 in words is "twenty-one million, seven hundred fifty thousand, one hundred five".