71681531 has 4 divisors (see below), whose sum is σ = 71699472. Its totient is φ = 71663592.

The previous prime is 71681521. The next prime is 71681549. The reversal of 71681531 is 13518617.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 71681531 - 2¹⁴ = 71665147 is a prime.

It is a super-2 number, since 2×71681531² = 10276483773007922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (71681521) 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, 41 + ... + 11973.

It is an arithmetic number, because the mean of its divisors is an integer number (17924868).

Almost surely, 2^71681531 is an apocalyptic number.

71681531 is a deficient number, since it is larger than the sum of its proper divisors (17941).

71681531 is a wasteful number, since it uses less digits than its factorization.

71681531 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17940.

The product of its digits is 5040, while the sum is 32.

The square root of 71681531 is about 8466.4946111127. The cubic root of 71681531 is about 415.4024856079.

The spelling of 71681531 in words is "seventy-one million, six hundred eighty-one thousand, five hundred thirty-one".