1998857117 has 2 divisors, whose sum is σ = 1998857118. Its totient is φ = 1998857116.

The previous prime is 1998857099. The next prime is 1998857143. The reversal of 1998857117 is 7117588991.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1228572601 + 770284516 = 35051^2 + 27754^2 .

It is a cyclic number.

It is not a de Polignac number, because 1998857117 - 2⁸ = 1998856861 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1998857197) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 999428558 + 999428559.

It is an arithmetic number, because the mean of its divisors is an integer number (999428559).

Almost surely, 2^1998857117 is an apocalyptic number.

It is an amenable number.

1998857117 is a deficient number, since it is larger than the sum of its proper divisors (1).

1998857117 is an equidigital number, since it uses as much as digits as its factorization.

1998857117 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1270080, while the sum is 56.

The square root of 1998857117 is about 44708.5799036382. The cubic root of 1998857117 is about 1259.6810137753.

The spelling of 1998857117 in words is "one billion, nine hundred ninety-eight million, eight hundred fifty-seven thousand, one hundred seventeen".