821863123 has 2 divisors, whose sum is σ = 821863124. Its totient is φ = 821863122.

The previous prime is 821863121. The next prime is 821863201. The reversal of 821863123 is 321368128.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 821863123 - 2¹ = 821863121 is a prime.

Together with 821863121, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (821863121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 410931561 + 410931562.

It is an arithmetic number, because the mean of its divisors is an integer number (410931562).

Almost surely, 2^821863123 is an apocalyptic number.

821863123 is a deficient number, since it is larger than the sum of its proper divisors (1).

821863123 is an equidigital number, since it uses as much as digits as its factorization.

821863123 is an evil number, because the sum of its binary digits is even.

The product of its digits is 13824, while the sum is 34.

The square root of 821863123 is about 28668.1552074772. The cubic root of 821863123 is about 936.6985142320.

The spelling of 821863123 in words is "eight hundred twenty-one million, eight hundred sixty-three thousand, one hundred twenty-three".