999855973 has 2 divisors, whose sum is σ = 999855974. Its totient is φ = 999855972.

The previous prime is 999855937. The next prime is 999855991. The reversal of 999855973 is 379558999.

It is a happy number.

Together with previous prime (999855937) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 819276129 + 180579844 = 28623^2 + 13438^2 .

It is a cyclic number.

It is not a de Polignac number, because 999855973 - 2²⁵ = 966301541 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (999855173) 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, 499927986 + 499927987.

It is an arithmetic number, because the mean of its divisors is an integer number (499927987).

Almost surely, 2^999855973 is an apocalyptic number.

It is an amenable number.

999855973 is a deficient number, since it is larger than the sum of its proper divisors (1).

999855973 is an equidigital number, since it uses as much as digits as its factorization.

999855973 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 27556200, while the sum is 64.

The square root of 999855973 is about 31620.4992528581. The cubic root of 999855973 is about 999.9519886950.

The spelling of 999855973 in words is "nine hundred ninety-nine million, eight hundred fifty-five thousand, nine hundred seventy-three".