21842147 has 2 divisors, whose sum is σ = 21842148. Its totient is φ = 21842146.

The previous prime is 21842137. The next prime is 21842179. The reversal of 21842147 is 74124812.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21842147 - 2⁴ = 21842131 is a prime.

It is not a weakly prime, because it can be changed into another prime (21842137) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10921073 + 10921074.

It is an arithmetic number, because the mean of its divisors is an integer number (10921074).

Almost surely, 2^21842147 is an apocalyptic number.

21842147 is a deficient number, since it is larger than the sum of its proper divisors (1).

21842147 is an equidigital number, since it uses as much as digits as its factorization.

21842147 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3584, while the sum is 29.

The square root of 21842147 is about 4673.5582803684. The cubic root of 21842147 is about 279.5321566556.

Adding to 21842147 its reverse (74124812), we get a palindrome (95966959).

The spelling of 21842147 in words is "twenty-one million, eight hundred forty-two thousand, one hundred forty-seven".