21331700 has 72 divisors (see below), whose sum is σ = 50856120. Its totient is φ = 7718400.

The previous prime is 21331693. The next prime is 21331729. The reversal of 21331700 is 713312.

It can be written as a sum of positive squares in 12 ways, for example, as 19749136 + 1582564 = 4444^2 + 1258^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 79166 + ... + 79434.

It is an arithmetic number, because the mean of its divisors is an integer number (706335).

Almost surely, 2^21331700 is an apocalyptic number.

21331700 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 21331700, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25428060).

21331700 is an abundant number, since it is smaller than the sum of its proper divisors (29524420).

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

21331700 is a wasteful number, since it uses less digits than its factorization.

21331700 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 357 (or 350 counting only the distinct ones).

The product of its (nonzero) digits is 126, while the sum is 17.

The square root of 21331700 is about 4618.6253366126. The cubic root of 21331700 is about 277.3374314966.

It can be divided in two parts, 213 and 31700, that added together give a palindrome (31913).

The spelling of 21331700 in words is "twenty-one million, three hundred thirty-one thousand, seven hundred".