21129336 has 56 divisors (see below), whose sum is σ = 59415480. Its totient is φ = 7041168.

The previous prime is 21129319. The next prime is 21129337. The reversal of 21129336 is 63392112.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a nude number because it is divisible by every one of its digits and also a Zuckerman number because it is divisible by the product of its digits.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21129337) by changing a digit.

It is a polite number, since it can be written in 13 ways as a sum of consecutive naturals, for example, 4021 + ... + 7643.

Almost surely, 2^21129336 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21129336, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29707740).

21129336 is an abundant number, since it is smaller than the sum of its proper divisors (38286144).

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

21129336 is an equidigital number, since it uses as much as digits as its factorization.

21129336 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3647 (or 3628 counting only the distinct ones).

The product of its digits is 1944, while the sum is 27.

The square root of 21129336 is about 4596.6657481266. The cubic root of 21129336 is about 276.4576528162.

The spelling of 21129336 in words is "twenty-one million, one hundred twenty-nine thousand, three hundred thirty-six".