21750001 has 16 divisors (see below), whose sum is σ = 26879104. Its totient is φ = 17138304.

The previous prime is 21749999. The next prime is 21750007. The reversal of 21750001 is 10005712.

It is a cyclic number.

It is not a de Polignac number, because 21750001 - 2¹ = 21749999 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21750007) 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, 41326 + ... + 41848.

It is an arithmetic number, because the mean of its divisors is an integer number (1679944).

Almost surely, 2^21750001 is an apocalyptic number.

It is an amenable number.

21750001 is a deficient number, since it is larger than the sum of its proper divisors (5129103).

21750001 is a wasteful number, since it uses less digits than its factorization.

21750001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1000.

The product of its (nonzero) digits is 70, while the sum is 16.

The square root of 21750001 is about 4663.6896337557. The cubic root of 21750001 is about 279.1385128609.

Adding to 21750001 its reverse (10005712), we get a palindrome (31755713).

The spelling of 21750001 in words is "twenty-one million, seven hundred fifty thousand, one".