21129300 has 108 divisors (see below), whose sum is σ = 70175196. Its totient is φ = 5299200.

The previous prime is 21129299. The next prime is 21129319. The reversal of 21129300 is 392112.

It is a happy number.

It can be written as a sum of positive squares in 6 ways, for example, as 6084 + 21123216 = 78^2 + 4596^2 .

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 14610 + ... + 15990.

Almost surely, 2^21129300 is an apocalyptic number.

21129300 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 21129300, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35087598).

21129300 is an abundant number, since it is smaller than the sum of its proper divisors (49045896).

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

21129300 is a wasteful number, since it uses less digits than its factorization.

21129300 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1418 (or 1408 counting only the distinct ones).

The product of its (nonzero) digits is 108, while the sum is 18.

The square root of 21129300 is about 4596.6618322430. The cubic root of 21129300 is about 276.4574958073.

The spelling of 21129300 in words is "twenty-one million, one hundred twenty-nine thousand, three hundred".