128771978 has 4 divisors (see below), whose sum is σ = 193157970. Its totient is φ = 64385988.

The previous prime is 128771969. The next prime is 128771983. The reversal of 128771978 is 879177821.

It is a happy number.

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

It can be written as a sum of positive squares in only one way, i.e., 113145769 + 15626209 = 10637^2 + 3953^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 32192993 + ... + 32192996.

Almost surely, 2^128771978 is an apocalyptic number.

128771978 is a deficient number, since it is larger than the sum of its proper divisors (64385992).

128771978 is an equidigital number, since it uses as much as digits as its factorization.

128771978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 64385991.

The product of its digits is 395136, while the sum is 50.

The square root of 128771978 is about 11347.7741429762. The cubic root of 128771978 is about 504.9795475820.

The spelling of 128771978 in words is "one hundred twenty-eight million, seven hundred seventy-one thousand, nine hundred seventy-eight".