21211700 has 18 divisors (see below), whose sum is σ = 46029606. Its totient is φ = 8484640.

The previous prime is 21211643. The next prime is 21211709. The reversal of 21211700 is 711212.

It can be written as a sum of positive squares in 3 ways, for example, as 14884 + 21196816 = 122^2 + 4604^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21211709) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 105959 + ... + 106158.

Almost surely, 2^21211700 is an apocalyptic number.

21211700 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21211700 is an abundant number, since it is smaller than the sum of its proper divisors (24817906).

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

21211700 is a wasteful number, since it uses less digits than its factorization.

21211700 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 212131 (or 212124 counting only the distinct ones).

The product of its (nonzero) digits is 28, while the sum is 14.

The square root of 21211700 is about 4605.6161368486. The cubic root of 21211700 is about 276.8164057736.

Adding to 21211700 its reverse (711212), we get a palindrome (21922912).

The spelling of 21211700 in words is "twenty-one million, two hundred eleven thousand, seven hundred".