21056370 has 128 divisors (see below), whose sum is σ = 58786560. Its totient is φ = 4792320.

The previous prime is 21056363. The next prime is 21056381. The reversal of 21056370 is 7365012.

It is a super-3 number, since 3×21056370³ (a number of 23 digits) contains 333 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21056370.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 397264 + ... + 397316.

It is an arithmetic number, because the mean of its divisors is an integer number (459270).

Almost surely, 2^21056370 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21056370, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29393280).

21056370 is an abundant number, since it is smaller than the sum of its proper divisors (37730190).

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

21056370 is a wasteful number, since it uses less digits than its factorization.

21056370 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 140.

The product of its (nonzero) digits is 1260, while the sum is 24.

The square root of 21056370 is about 4588.7220443169. The cubic root of 21056370 is about 276.1390551129.

The spelling of 21056370 in words is "twenty-one million, fifty-six thousand, three hundred seventy".