71643681 has 12 divisors (see below), whose sum is σ = 103606308. Its totient is φ = 47706624.

The previous prime is 71643673. The next prime is 71643701. The reversal of 71643681 is 18634617.

71643681 is a `hidden beast` number, since 7 + 1 + 643 + 6 + 8 + 1 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 38638656 + 33005025 = 6216^2 + 5745^2 .

It is not a de Polignac number, because 71643681 - 2³ = 71643673 is a prime.

It is a super-2 number, since 2×71643681² = 10265634054459522, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (71643631) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 4401 + ... + 12753.

It is an arithmetic number, because the mean of its divisors is an integer number (8633859).

Almost surely, 2^71643681 is an apocalyptic number.

It is an amenable number.

71643681 is a deficient number, since it is larger than the sum of its proper divisors (31962627).

71643681 is a wasteful number, since it uses less digits than its factorization.

71643681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9312 (or 9309 counting only the distinct ones).

The product of its digits is 24192, while the sum is 36.

The square root of 71643681 is about 8464.2590343160. The cubic root of 71643681 is about 415.3293577413.

The spelling of 71643681 in words is "seventy-one million, six hundred forty-three thousand, six hundred eighty-one".