21188708 has 6 divisors (see below), whose sum is σ = 37080246. Its totient is φ = 10594352.

The previous prime is 21188707. The next prime is 21188719. The reversal of 21188708 is 80788112.

It can be written as a sum of positive squares in only one way, i.e., 18472804 + 2715904 = 4298^2 + 1648^2 .

It is a super-2 number, since 2×21188708² = 897922693418528, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21188701) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2648585 + ... + 2648592.

It is an arithmetic number, because the mean of its divisors is an integer number (6180041).

Almost surely, 2^21188708 is an apocalyptic number.

It is an amenable number.

21188708 is a deficient number, since it is larger than the sum of its proper divisors (15891538).

21188708 is a wasteful number, since it uses less digits than its factorization.

21188708 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5297181 (or 5297179 counting only the distinct ones).

The product of its (nonzero) digits is 7168, while the sum is 35.

The square root of 21188708 is about 4603.1193771181. The cubic root of 21188708 is about 276.7163530705.

The spelling of 21188708 in words is "twenty-one million, one hundred eighty-eight thousand, seven hundred eight".