21207100 has 36 divisors (see below), whose sum is σ = 47510848. Its totient is φ = 8208000.

The previous prime is 21207037. The next prime is 21207101. The reversal of 21207100 is 170212.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21207101) 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 11 ways as a sum of consecutive naturals, for example, 321 + ... + 6520.

Almost surely, 2^21207100 is an apocalyptic number.

21207100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21207100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23755424).

21207100 is an abundant number, since it is smaller than the sum of its proper divisors (26303748).

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

21207100 is a wasteful number, since it uses less digits than its factorization.

21207100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6886 (or 6879 counting only the distinct ones).

The product of its (nonzero) digits is 28, while the sum is 13.

The square root of 21207100 is about 4605.1167194763. The cubic root of 21207100 is about 276.7963940580.

Adding to 21207100 its reverse (170212), we get a palindrome (21377312).

The spelling of 21207100 in words is "twenty-one million, two hundred seven thousand, one hundred".