21858163 has 2 divisors, whose sum is σ = 21858164. Its totient is φ = 21858162.

The previous prime is 21858127. The next prime is 21858197. The reversal of 21858163 is 36185812.

It is an a-pointer prime, because the next prime (21858197) can be obtained adding 21858163 to its sum of digits (34).

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21858163 - 2⁹ = 21857651 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is not a weakly prime, because it can be changed into another prime (21858563) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10929081 + 10929082.

It is an arithmetic number, because the mean of its divisors is an integer number (10929082).

Almost surely, 2^21858163 is an apocalyptic number.

21858163 is a deficient number, since it is larger than the sum of its proper divisors (1).

21858163 is an equidigital number, since it uses as much as digits as its factorization.

21858163 is an evil number, because the sum of its binary digits is even.

The product of its digits is 11520, while the sum is 34.

The square root of 21858163 is about 4675.2714359703. The cubic root of 21858163 is about 279.6004633289.

The spelling of 21858163 in words is "twenty-one million, eight hundred fifty-eight thousand, one hundred sixty-three".