21860243 has 2 divisors, whose sum is σ = 21860244. Its totient is φ = 21860242.

The previous prime is 21860227. The next prime is 21860263. The reversal of 21860243 is 34206812.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21860243 - 2⁴ = 21860227 is a prime.

It is not a weakly prime, because it can be changed into another prime (21860263) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10930121 + 10930122.

It is an arithmetic number, because the mean of its divisors is an integer number (10930122).

Almost surely, 2^21860243 is an apocalyptic number.

21860243 is a deficient number, since it is larger than the sum of its proper divisors (1).

21860243 is an equidigital number, since it uses as much as digits as its factorization.

21860243 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2304, while the sum is 26.

The square root of 21860243 is about 4675.4938776561. The cubic root of 21860243 is about 279.6093318771.

The spelling of 21860243 in words is "twenty-one million, eight hundred sixty thousand, two hundred forty-three".