1998421658 has 4 divisors (see below), whose sum is σ = 2997632490. Its totient is φ = 999210828.

The previous prime is 1998421619. The next prime is 1998421669. The reversal of 1998421658 is 8561248991.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 1543154089 + 455267569 = 39283^2 + 21337^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 499605413 + ... + 499605416.

Almost surely, 2^1998421658 is an apocalyptic number.

1998421658 is a deficient number, since it is larger than the sum of its proper divisors (999210832).

1998421658 is an equidigital number, since it uses as much as digits as its factorization.

1998421658 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 999210831.

The product of its digits is 1244160, while the sum is 53.

The square root of 1998421658 is about 44703.7096670959. The cubic root of 1998421658 is about 1259.5895316197.

The spelling of 1998421658 in words is "one billion, nine hundred ninety-eight million, four hundred twenty-one thousand, six hundred fifty-eight".