52161605721 has 20 divisors (see below), whose sum is σ = 78105558564. Its totient is φ = 34691781600.

The previous prime is 52161605719. The next prime is 52161605729. The reversal of 52161605721 is 12750616125.

52161605721 is a `hidden beast` number, since 5 + 21 + 6 + 1 + 60 + 572 + 1 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 12097580121 + 40064025600 = 109989^2 + 200160^2 .

It is not a de Polignac number, because 52161605721 - 2¹ = 52161605719 is a prime.

It is a super-2 number, since 2×52161605721² (a number of 22 digits) contains 22 as substring.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (52161605729) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 730710 + ... + 798911.

Almost surely, 2^52161605721 is an apocalyptic number.

It is an amenable number.

52161605721 is a deficient number, since it is larger than the sum of its proper divisors (25943952843).

52161605721 is a wasteful number, since it uses less digits than its factorization.

52161605721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1530054 (or 1530045 counting only the distinct ones).

The product of its (nonzero) digits is 25200, while the sum is 36.

The spelling of 52161605721 in words is "fifty-two billion, one hundred sixty-one million, six hundred five thousand, seven hundred twenty-one".