1998505728 has 216 divisors, whose sum is σ = 6160452480. Its totient is φ = 621250560.

The previous prime is 1998505651. The next prime is 1998505757. The reversal of 1998505728 is 8275058991.

1998505728 is a `hidden beast` number, since 19 + 9 + 8 + 50 + 572 + 8 = 666.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3107775 + ... + 3108417.

Almost surely, 2^1998505728 is an apocalyptic number.

1998505728 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1998505728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3080226240).

1998505728 is an abundant number, since it is smaller than the sum of its proper divisors (4161946752).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1998505728 is a wasteful number, since it uses less digits than its factorization.

1998505728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 755 (or 738 counting only the distinct ones).

The product of its (nonzero) digits is 1814400, while the sum is 54.

The square root of 1998505728 is about 44704.6499594841. The cubic root of 1998505728 is about 1259.6071942598.

The spelling of 1998505728 in words is "one billion, nine hundred ninety-eight million, five hundred five thousand, seven hundred twenty-eight".