164428561681 has 18 divisors (see below), whose sum is σ = 171842246646. Its totient is φ = 157329216000.

The previous prime is 164428561597. The next prime is 164428561691. The reversal of 164428561681 is 186165824461.

It can be written as a sum of positive squares in 3 ways, for example, as 13406166225 + 151022395456 = 115785^2 + 388616^2 .

It is not a de Polignac number, because 164428561681 - 2¹⁹ = 164428037393 is a prime.

It is a super-3 number, since 3×164428561681³ (a number of 35 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Smith number, since the sum of its digits (52) coincides with the sum of the digits of its prime factors.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (164428561691) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 7601281 + ... + 7622881.

Almost surely, 2^164428561681 is an apocalyptic number.

It is an amenable number.

164428561681 is a deficient number, since it is larger than the sum of its proper divisors (7413684965).

164428561681 is an frugal number, since it uses more digits than its factorization.

164428561681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21841 (or 21721 counting only the distinct ones).

The product of its digits is 2211840, while the sum is 52.

The spelling of 164428561681 in words is "one hundred sixty-four billion, four hundred twenty-eight million, five hundred sixty-one thousand, six hundred eighty-one".