1998129997 has 2 divisors, whose sum is σ = 1998129998. Its totient is φ = 1998129996.

The previous prime is 1998129979. The next prime is 1998130061. The reversal of 1998129997 is 7999218991.

Together with previous prime (1998129979) it forms an Ormiston pair, because they use the same digits, order apart.

It is an a-pointer prime, because the next prime (1998130061) can be obtained adding 1998129997 to its sum of digits (64).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1647466921 + 350663076 = 40589^2 + 18726^2 .

It is a cyclic number.

It is not a de Polignac number, because 1998129997 - 2¹¹ = 1998127949 is a prime.

It is a super-2 number, since 2×1998129997² = 7985046969822440018, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1998129967) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 999064998 + 999064999.

It is an arithmetic number, because the mean of its divisors is an integer number (999064999).

Almost surely, 2^1998129997 is an apocalyptic number.

It is an amenable number.

1998129997 is a deficient number, since it is larger than the sum of its proper divisors (1).

1998129997 is an equidigital number, since it uses as much as digits as its factorization.

1998129997 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6613488, while the sum is 64.

The square root of 1998129997 is about 44700.4473914971. The cubic root of 1998129997 is about 1259.5282514232.

The spelling of 1998129997 in words is "one billion, nine hundred ninety-eight million, one hundred twenty-nine thousand, nine hundred ninety-seven".