128771977 has 4 divisors (see below), whose sum is σ = 133212420. Its totient is φ = 124331536.

The previous prime is 128771969. The next prime is 128771983. The reversal of 128771977 is 779177821.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 779177821 = 19 ⋅41009359.

It can be written as a sum of positive squares in 2 ways, for example, as 101929216 + 26842761 = 10096^2 + 5181^2 .

It is a cyclic number.

It is not a de Polignac number, because 128771977 - 2³ = 128771969 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 128771977.

It is not an unprimeable number, because it can be changed into a prime (128771947) 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, 2220178 + ... + 2220235.

It is an arithmetic number, because the mean of its divisors is an integer number (33303105).

Almost surely, 2^128771977 is an apocalyptic number.

It is an amenable number.

128771977 is a deficient number, since it is larger than the sum of its proper divisors (4440443).

128771977 is an equidigital number, since it uses as much as digits as its factorization.

128771977 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4440442.

The product of its digits is 345744, while the sum is 49.

The square root of 128771977 is about 11347.7740989147. The cubic root of 128771977 is about 504.9795462748.

The spelling of 128771977 in words is "one hundred twenty-eight million, seven hundred seventy-one thousand, nine hundred seventy-seven".