71721571 has 4 divisors (see below), whose sum is σ = 71843112. Its totient is φ = 71600032.

The previous prime is 71721563. The next prime is 71721649. The reversal of 71721571 is 17512717.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 17512717 = 47 ⋅372611.

It is a cyclic number.

It is not a de Polignac number, because 71721571 - 2³ = 71721563 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (71721511) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 59881 + ... + 61066.

It is an arithmetic number, because the mean of its divisors is an integer number (17960778).

Almost surely, 2^71721571 is an apocalyptic number.

71721571 is a deficient number, since it is larger than the sum of its proper divisors (121541).

71721571 is a wasteful number, since it uses less digits than its factorization.

71721571 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 121540.

The product of its digits is 3430, while the sum is 31.

The square root of 71721571 is about 8468.8588959788. The cubic root of 71721571 is about 415.4798166365.

The spelling of 71721571 in words is "seventy-one million, seven hundred twenty-one thousand, five hundred seventy-one".