71535721 has 4 divisors (see below), whose sum is σ = 74002500. Its totient is φ = 69068944.

The previous prime is 71535713. The next prime is 71535733. The reversal of 71535721 is 12753517.

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

It can be written as a sum of positive squares in 2 ways, for example, as 60279696 + 11256025 = 7764^2 + 3355^2 .

It is a cyclic number.

It is not a de Polignac number, because 71535721 - 2³ = 71535713 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (71565721) 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, 1233346 + ... + 1233403.

It is an arithmetic number, because the mean of its divisors is an integer number (18500625).

Almost surely, 2^71535721 is an apocalyptic number.

It is an amenable number.

71535721 is a deficient number, since it is larger than the sum of its proper divisors (2466779).

71535721 is a wasteful number, since it uses less digits than its factorization.

71535721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2466778.

The product of its digits is 7350, while the sum is 31.

The square root of 71535721 is about 8457.8792259053. The cubic root of 71535721 is about 415.1206326621.

The spelling of 71535721 in words is "seventy-one million, five hundred thirty-five thousand, seven hundred twenty-one".