128217780 has 36 divisors (see below), whose sum is σ = 388927812. Its totient is φ = 34191360.

The previous prime is 128217773. The next prime is 128217809. The reversal of 128217780 is 87712821.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 32216976 + 96000804 = 5676^2 + 9798^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 355981 + ... + 356340.

Almost surely, 2^128217780 is an apocalyptic number.

128217780 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

128217780 is an abundant number, since it is smaller than the sum of its proper divisors (260710032).

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

128217780 is a wasteful number, since it uses less digits than its factorization.

128217780 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 712336 (or 712331 counting only the distinct ones).

The product of its (nonzero) digits is 12544, while the sum is 36.

The square root of 128217780 is about 11323.3290157974. The cubic root of 128217780 is about 504.2540763531.

The spelling of 128217780 in words is "one hundred twenty-eight million, two hundred seventeen thousand, seven hundred eighty".