21606100 has 18 divisors (see below), whose sum is σ = 46885454. Its totient is φ = 8642400.

The previous prime is 21606083. The next prime is 21606119. The reversal of 21606100 is 160612.

It can be written as a sum of positive squares in 3 ways, for example, as 501264 + 21104836 = 708^2 + 4594^2 .

It is a congruent number.

It is an unprimeable number.

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 5 ways as a sum of consecutive naturals, for example, 107931 + ... + 108130.

Almost surely, 2^21606100 is an apocalyptic number.

21606100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21606100 is an abundant number, since it is smaller than the sum of its proper divisors (25279354).

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

21606100 is a wasteful number, since it uses less digits than its factorization.

21606100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 216075 (or 216068 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 16.

The square root of 21606100 is about 4648.2362246340. The cubic root of 21606100 is about 278.5215439306.

Adding to 21606100 its reverse (160612), we get a palindrome (21766712).

The spelling of 21606100 in words is "twenty-one million, six hundred six thousand, one hundred".