21057246 has 80 divisors (see below), whose sum is σ = 55756800. Its totient is φ = 5812560.

The previous prime is 21057241. The next prime is 21057247. The reversal of 21057246 is 64275012.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21057241) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 34855 + ... + 35453.

It is an arithmetic number, because the mean of its divisors is an integer number (696960).

Almost surely, 2^21057246 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21057246, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27878400).

21057246 is an abundant number, since it is smaller than the sum of its proper divisors (34699554).

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

21057246 is a wasteful number, since it uses less digits than its factorization.

21057246 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 651 (or 642 counting only the distinct ones).

The product of its (nonzero) digits is 3360, while the sum is 27.

The square root of 21057246 is about 4588.8174947365. The cubic root of 21057246 is about 276.1428844285.

The spelling of 21057246 in words is "twenty-one million, fifty-seven thousand, two hundred forty-six".