21056243 has 8 divisors (see below), whose sum is σ = 22932000. Its totient is φ = 19217088.

The previous prime is 21056227. The next prime is 21056249. The reversal of 21056243 is 34265012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21056243 - 2⁴ = 21056227 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21056249) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7943 + ... + 10256.

It is an arithmetic number, because the mean of its divisors is an integer number (2866500).

Almost surely, 2^21056243 is an apocalyptic number.

21056243 is a deficient number, since it is larger than the sum of its proper divisors (1875757).

21056243 is a wasteful number, since it uses less digits than its factorization.

21056243 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18301.

The product of its (nonzero) digits is 1440, while the sum is 23.

The square root of 21056243 is about 4588.7082060205. The cubic root of 21056243 is about 276.1384999407.

The spelling of 21056243 in words is "twenty-one million, fifty-six thousand, two hundred forty-three".