21307700 has 36 divisors (see below), whose sum is σ = 47374572. Its totient is φ = 8313600.

The previous prime is 21307687. The next prime is 21307753. The reversal of 21307700 is 770312.

It can be written as a sum of positive squares in 6 ways, for example, as 3952144 + 17355556 = 1988^2 + 4166^2 .

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1502 + ... + 6698.

Almost surely, 2^21307700 is an apocalyptic number.

21307700 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 21307700, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23687286).

21307700 is an abundant number, since it is smaller than the sum of its proper divisors (26066872).

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

21307700 is a wasteful number, since it uses less digits than its factorization.

21307700 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5252 (or 5245 counting only the distinct ones).

The product of its (nonzero) digits is 294, while the sum is 20.

The square root of 21307700 is about 4616.0264297337. The cubic root of 21307700 is about 277.2333829656.

The spelling of 21307700 in words is "twenty-one million, three hundred seven thousand, seven hundred".