1988728997 has 4 divisors (see below), whose sum is σ = 1995123936. Its totient is φ = 1982334060.

The previous prime is 1988728991. The next prime is 1988729009. The reversal of 1988728997 is 7998278891.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 7998278891 = 59 ⋅135564049.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1988728997 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1988728991) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3197003 + ... + 3197624.

It is an arithmetic number, because the mean of its divisors is an integer number (498780984).

Almost surely, 2^1988728997 is an apocalyptic number.

It is an amenable number.

1988728997 is a deficient number, since it is larger than the sum of its proper divisors (6394939).

1988728997 is an equidigital number, since it uses as much as digits as its factorization.

1988728997 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6394938.

The product of its digits is 36578304, while the sum is 68.

The square root of 1988728997 is about 44595.1678660368. The cubic root of 1988728997 is about 1257.5498276364.

It can be divided in two parts, 19887 and 28997, that added together give a palindrome (48884).

The spelling of 1988728997 in words is "one billion, nine hundred eighty-eight million, seven hundred twenty-eight thousand, nine hundred ninety-seven".