128477774821 has 4 divisors (see below), whose sum is σ = 140157572544. Its totient is φ = 116797977100.

The previous prime is 128477774809. The next prime is 128477774833.

128477774821 is nontrivially palindromic in base 10.

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.

It is an interprime number because it is at equal distance from previous prime (128477774809) and next prime (128477774833).

It is a cyclic number.

It is not a de Polignac number, because 128477774821 - 2¹⁵ = 128477742053 is a prime.

It is a Smith number, since the sum of its digits (58) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (128477774851) 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, 5839898845 + ... + 5839898866.

It is an arithmetic number, because the mean of its divisors is an integer number (35039393136).

Almost surely, 2^128477774821 is an apocalyptic number.

128477774821 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

128477774821 is a deficient number, since it is larger than the sum of its proper divisors (11679797723).

128477774821 is a wasteful number, since it uses less digits than its factorization.

128477774821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11679797722.

The product of its digits is 9834496, while the sum is 58.

The spelling of 128477774821 in words is "one hundred twenty-eight billion, four hundred seventy-seven million, seven hundred seventy-four thousand, eight hundred twenty-one".