128631693 has 4 divisors (see below), whose sum is σ = 171508928. Its totient is φ = 85754460.

The previous prime is 128631677. The next prime is 128631703. The reversal of 128631693 is 396136821.

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 not a de Polignac number, because 128631693 - 2⁴ = 128631677 is a prime.

It is a super-2 number, since 2×128631693² = 33092224888092498, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (128631193) 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, 21438613 + ... + 21438618.

It is an arithmetic number, because the mean of its divisors is an integer number (42877232).

Almost surely, 2^128631693 is an apocalyptic number.

It is an amenable number.

128631693 is a deficient number, since it is larger than the sum of its proper divisors (42877235).

128631693 is an equidigital number, since it uses as much as digits as its factorization.

128631693 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42877234.

The product of its digits is 46656, while the sum is 39.

The square root of 128631693 is about 11341.5912904671. The cubic root of 128631693 is about 504.7961049899.

The spelling of 128631693 in words is "one hundred twenty-eight million, six hundred thirty-one thousand, six hundred ninety-three".