21872100 has 36 divisors (see below), whose sum is σ = 63284144. Its totient is φ = 5832480.

The previous prime is 21872087. The next prime is 21872107. The reversal of 21872100 is 127812.

It is not an unprimeable number, because it can be changed into a prime (21872107) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 36154 + ... + 36753.

Almost surely, 2^21872100 is an apocalyptic number.

21872100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21872100 is an abundant number, since it is smaller than the sum of its proper divisors (41412044).

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

21872100 is a wasteful number, since it uses less digits than its factorization.

21872100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 72924 (or 72917 counting only the distinct ones).

The product of its (nonzero) digits is 224, while the sum is 21.

The square root of 21872100 is about 4676.7617001511. The cubic root of 21872100 is about 279.6598761249.

Adding to 21872100 its reverse (127812), we get a palindrome (21999912).

The spelling of 21872100 in words is "twenty-one million, eight hundred seventy-two thousand, one hundred".