1998423211731 has 4 divisors (see below), whose sum is σ = 2664564282312. Its totient is φ = 1332282141152.

The previous prime is 1998423211727. The next prime is 1998423211739. The reversal of 1998423211731 is 1371123248991.

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

It is a cyclic number.

It is not a de Polignac number, because 1998423211731 - 2² = 1998423211727 is a prime.

It is a super-2 number, since 2×1998423211731² (a number of 25 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (1998423211739) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 333070535286 + ... + 333070535291.

It is an arithmetic number, because the mean of its divisors is an integer number (666141070578).

Almost surely, 2^{1998423211731} is an apocalyptic number.

1998423211731 is a deficient number, since it is larger than the sum of its proper divisors (666141070581).

1998423211731 is an equidigital number, since it uses as much as digits as its factorization.

1998423211731 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 666141070580.

The product of its digits is 653184, while the sum is 51.

The spelling of 1998423211731 in words is "one trillion, nine hundred ninety-eight billion, four hundred twenty-three million, two hundred eleven thousand, seven hundred thirty-one".