71943991 has 4 divisors (see below), whose sum is σ = 82221712. Its totient is φ = 61666272.

The previous prime is 71943979. The next prime is 71944001. The reversal of 71943991 is 19934917.

It is a happy number.

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 71943991 - 2¹⁵ = 71911223 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (71943491) 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, 5138850 + ... + 5138863.

It is an arithmetic number, because the mean of its divisors is an integer number (20555428).

Almost surely, 2^71943991 is an apocalyptic number.

71943991 is a deficient number, since it is larger than the sum of its proper divisors (10277721).

71943991 is a wasteful number, since it uses less digits than its factorization.

71943991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10277720.

The product of its digits is 61236, while the sum is 43.

The square root of 71943991 is about 8481.9803701730. The cubic root of 71943991 is about 415.9088630943.

The spelling of 71943991 in words is "seventy-one million, nine hundred forty-three thousand, nine hundred ninety-one".