21129100 has 18 divisors (see below), whose sum is σ = 45850364. Its totient is φ = 8451600.

The previous prime is 21129077. The next prime is 21129107. The reversal of 21129100 is 192112.

It is not an unprimeable number, because it can be changed into a prime (21129107) 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, 105546 + ... + 105745.

Almost surely, 2^21129100 is an apocalyptic number.

21129100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21129100 is an abundant number, since it is smaller than the sum of its proper divisors (24721264).

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

21129100 is a wasteful number, since it uses less digits than its factorization.

21129100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 211305 (or 211298 counting only the distinct ones).

The product of its (nonzero) digits is 36, while the sum is 16.

The square root of 21129100 is about 4596.6400772738. The cubic root of 21129100 is about 276.4566235324.

The spelling of 21129100 in words is "twenty-one million, one hundred twenty-nine thousand, one hundred".