21037720 has 64 divisors (see below), whose sum is σ = 52164000. Its totient is φ = 7572480.

The previous prime is 21037703. The next prime is 21037727. The reversal of 21037720 is 2773012.

It is a Harshad number since it is a multiple of its sum of digits (22).

It is a junction number, because it is equal to n+sod(n) for n = 21037691 and 21037700.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21037727) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 60106 + ... + 60454.

Almost surely, 2^21037720 is an apocalyptic number.

21037720 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 21037720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26082000).

21037720 is an abundant number, since it is smaller than the sum of its proper divisors (31126280).

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

21037720 is a wasteful number, since it uses less digits than its factorization.

21037720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 508 (or 504 counting only the distinct ones).

The product of its (nonzero) digits is 588, while the sum is 22.

The square root of 21037720 is about 4586.6894379280. The cubic root of 21037720 is about 276.0575039464.

The spelling of 21037720 in words is "twenty-one million, thirty-seven thousand, seven hundred twenty".