820423657 has 2 divisors, whose sum is σ = 820423658. Its totient is φ = 820423656.

The previous prime is 820423631. The next prime is 820423663. The reversal of 820423657 is 756324028.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 438651136 + 381772521 = 20944^2 + 19539^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-820423657 is a prime.

It is not a weakly prime, because it can be changed into another prime (820423687) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 410211828 + 410211829.

It is an arithmetic number, because the mean of its divisors is an integer number (410211829).

Almost surely, 2^820423657 is an apocalyptic number.

It is an amenable number.

820423657 is a deficient number, since it is larger than the sum of its proper divisors (1).

820423657 is an equidigital number, since it uses as much as digits as its factorization.

820423657 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 80640, while the sum is 37.

The square root of 820423657 is about 28643.0385434227. The cubic root of 820423657 is about 936.1513291891.

The spelling of 820423657 in words is "eight hundred twenty million, four hundred twenty-three thousand, six hundred fifty-seven".