1998125081 has 2 divisors, whose sum is σ = 1998125082. Its totient is φ = 1998125080.

The previous prime is 1998125047. The next prime is 1998125113. The reversal of 1998125081 is 1805218991.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1939081225 + 59043856 = 44035^2 + 7684^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1998125081 is a prime.

It is a super-2 number, since 2×1998125081² = 7985007678642513122, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1998125581) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 999062540 + 999062541.

It is an arithmetic number, because the mean of its divisors is an integer number (999062541).

Almost surely, 2^1998125081 is an apocalyptic number.

It is an amenable number.

1998125081 is a deficient number, since it is larger than the sum of its proper divisors (1).

1998125081 is an equidigital number, since it uses as much as digits as its factorization.

1998125081 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 51840, while the sum is 44.

The square root of 1998125081 is about 44700.3924031993. The cubic root of 1998125081 is about 1259.5272184831.

The spelling of 1998125081 in words is "one billion, nine hundred ninety-eight million, one hundred twenty-five thousand, eighty-one".