21037320 has 160 divisors (see below), whose sum is σ = 72832320. Its totient is φ = 5443200.

The previous prime is 21037301. The next prime is 21037339. The reversal of 21037320 is 2373012.

It is an interprime number because it is at equal distance from previous prime (21037301) and next prime (21037339).

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

It is a junction number, because it is equal to n+sod(n) for n = 21037293 and 21037302.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 139245 + ... + 139395.

It is an arithmetic number, because the mean of its divisors is an integer number (455202).

Almost surely, 2^21037320 is an apocalyptic number.

21037320 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 21037320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36416160).

21037320 is an abundant number, since it is smaller than the sum of its proper divisors (51795000).

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

21037320 is a wasteful number, since it uses less digits than its factorization.

21037320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 217 (or 204 counting only the distinct ones).

The product of its (nonzero) digits is 252, while the sum is 18.

The square root of 21037320 is about 4586.6458332860. The cubic root of 21037320 is about 276.0557543319.

The spelling of 21037320 in words is "twenty-one million, thirty-seven thousand, three hundred twenty".