21750012 has 24 divisors (see below), whose sum is σ = 56389200. Its totient is φ = 7249968.

The previous prime is 21750011. The next prime is 21750017. The reversal of 21750012 is 21005712.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21750011) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 100587 + ... + 100802.

It is an arithmetic number, because the mean of its divisors is an integer number (2349550).

Almost surely, 2^21750012 is an apocalyptic number.

It is an amenable number.

21750012 is an abundant number, since it is smaller than the sum of its proper divisors (34639188).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21750012 is a wasteful number, since it uses less digits than its factorization.

21750012 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 201402 (or 201394 counting only the distinct ones).

The product of its (nonzero) digits is 140, while the sum is 18.

The square root of 21750012 is about 4663.6908130793. The cubic root of 21750012 is about 279.1385599187.

Adding to 21750012 its reverse (21005712), we get a palindrome (42755724).

The spelling of 21750012 in words is "twenty-one million, seven hundred fifty thousand, twelve".