820755389 has 2 divisors, whose sum is σ = 820755390. Its totient is φ = 820755388.

The previous prime is 820755373. The next prime is 820755443. The reversal of 820755389 is 983557028.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 791972164 + 28783225 = 28142^2 + 5365^2 .

It is a cyclic number.

It is not a de Polignac number, because 820755389 - 2⁴ = 820755373 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (820755329) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 410377694 + 410377695.

It is an arithmetic number, because the mean of its divisors is an integer number (410377695).

Almost surely, 2^820755389 is an apocalyptic number.

It is an amenable number.

820755389 is a deficient number, since it is larger than the sum of its proper divisors (1).

820755389 is an equidigital number, since it uses as much as digits as its factorization.

820755389 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 604800, while the sum is 47.

The square root of 820755389 is about 28648.8287544186. The cubic root of 820755389 is about 936.2774873852.

The spelling of 820755389 in words is "eight hundred twenty million, seven hundred fifty-five thousand, three hundred eighty-nine".