163128781 has 4 divisors (see below), whose sum is σ = 165094272. Its totient is φ = 161163292.

The previous prime is 163128769. The next prime is 163128827. The reversal of 163128781 is 187821361.

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 a cyclic number.

It is not a de Polignac number, because 163128781 - 2¹³ = 163120589 is a prime.

It is a super-2 number, since 2×163128781² = 53221998381091922, which contains 22 as substring.

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 163128781.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (163128881) 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, 982621 + ... + 982786.

It is an arithmetic number, because the mean of its divisors is an integer number (41273568).

Almost surely, 2^163128781 is an apocalyptic number.

It is an amenable number.

163128781 is a deficient number, since it is larger than the sum of its proper divisors (1965491).

163128781 is an equidigital number, since it uses as much as digits as its factorization.

163128781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1965490.

The product of its digits is 16128, while the sum is 37.

The square root of 163128781 is about 12772.1877922304. The cubic root of 163128781 is about 546.3993788432.

The spelling of 163128781 in words is "one hundred sixty-three million, one hundred twenty-eight thousand, seven hundred eighty-one".