21750006 has 16 divisors (see below), whose sum is σ = 44676144. Its totient is φ = 7053984.

The previous prime is 21749999. The next prime is 21750007. The reversal of 21750006 is 60005712.

It is a super-2 number, since 2×21750006² = 946125522000072, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21750007) 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, 48765 + ... + 49208.

It is an arithmetic number, because the mean of its divisors is an integer number (2792259).

Almost surely, 2^21750006 is an apocalyptic number.

21750006 is an abundant number, since it is smaller than the sum of its proper divisors (22926138).

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

21750006 is a wasteful number, since it uses less digits than its factorization.

21750006 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 98015.

The product of its (nonzero) digits is 420, while the sum is 21.

The square root of 21750006 is about 4663.6901698119. The cubic root of 21750006 is about 279.1385342508.

Adding to 21750006 its reverse (60005712), we get a palindrome (81755718).

The spelling of 21750006 in words is "twenty-one million, seven hundred fifty thousand, six".