128997720 has 48 divisors (see below), whose sum is σ = 419243760. Its totient is φ = 34399296.

The previous prime is 128997719. The next prime is 128997763. The reversal of 128997720 is 27799821.

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 178804 + ... + 179523.

It is an arithmetic number, because the mean of its divisors is an integer number (8734245).

Almost surely, 2^128997720 is an apocalyptic number.

128997720 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

128997720 is an abundant number, since it is smaller than the sum of its proper divisors (290246040).

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

128997720 is a wasteful number, since it uses less digits than its factorization.

128997720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 358344 (or 358337 counting only the distinct ones).

The product of its (nonzero) digits is 127008, while the sum is 45.

The square root of 128997720 is about 11357.7163197537. The cubic root of 128997720 is about 505.2744578750.

The spelling of 128997720 in words is "one hundred twenty-eight million, nine hundred ninety-seven thousand, seven hundred twenty".