21129200 has 60 divisors (see below), whose sum is σ = 51363528. Its totient is φ = 8352000.

The previous prime is 21129191. The next prime is 21129209. The reversal of 21129200 is 292112.

It is an interprime number because it is at equal distance from previous prime (21129191) and next prime (21129209).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21129209) 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, 40139 + ... + 40661.

Almost surely, 2^21129200 is an apocalyptic number.

21129200 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 21129200, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25681764).

21129200 is an abundant number, since it is smaller than the sum of its proper divisors (30234328).

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

21129200 is a wasteful number, since it uses less digits than its factorization.

21129200 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 642 (or 631 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 17.

The square root of 21129200 is about 4596.6509547713. The cubic root of 21129200 is about 276.4570596705.

The spelling of 21129200 in words is "twenty-one million, one hundred twenty-nine thousand, two hundred".