820421443 has 2 divisors, whose sum is σ = 820421444. Its totient is φ = 820421442.

The previous prime is 820421359. The next prime is 820421447. The reversal of 820421443 is 344124028.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-820421443 is a prime.

It is equal to p_42141961 and since 820421443 and 42141961 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (820421447) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 410210721 + 410210722.

It is an arithmetic number, because the mean of its divisors is an integer number (410210722).

Almost surely, 2^820421443 is an apocalyptic number.

820421443 is a deficient number, since it is larger than the sum of its proper divisors (1).

820421443 is an equidigital number, since it uses as much as digits as its factorization.

820421443 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6144, while the sum is 28.

The square root of 820421443 is about 28642.9998952624. Note that the first 3 decimals coincide. The cubic root of 820421443 is about 936.1504870873.

The spelling of 820421443 in words is "eight hundred twenty million, four hundred twenty-one thousand, four hundred forty-three".