128386861 has 4 divisors (see below), whose sum is σ = 129829500. Its totient is φ = 126944224.

The previous prime is 128386859. The next prime is 128386889. The reversal of 128386861 is 168683821.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 168683821 = 103 ⋅1637707.

It can be written as a sum of positive squares in 2 ways, for example, as 49070025 + 79316836 = 7005^2 + 8906^2 .

It is a cyclic number.

It is not a de Polignac number, because 128386861 - 2¹ = 128386859 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (128386801) 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, 721186 + ... + 721363.

It is an arithmetic number, because the mean of its divisors is an integer number (32457375).

Almost surely, 2^128386861 is an apocalyptic number.

It is an amenable number.

128386861 is a deficient number, since it is larger than the sum of its proper divisors (1442639).

128386861 is an equidigital number, since it uses as much as digits as its factorization.

128386861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1442638.

The product of its digits is 110592, while the sum is 43.

The square root of 128386861 is about 11330.7926024617. The cubic root of 128386861 is about 504.4756325562.

The spelling of 128386861 in words is "one hundred twenty-eight million, three hundred eighty-six thousand, eight hundred sixty-one".