71240721 has 4 divisors (see below), whose sum is σ = 94987632. Its totient is φ = 47493812.

The previous prime is 71240717. The next prime is 71240731. The reversal of 71240721 is 12704217.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 71240721 - 2² = 71240717 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 71240691 and 71240700.

It is not an unprimeable number, because it can be changed into a prime (71240711) 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, 11873451 + ... + 11873456.

It is an arithmetic number, because the mean of its divisors is an integer number (23746908).

Almost surely, 2^71240721 is an apocalyptic number.

It is an amenable number.

71240721 is a deficient number, since it is larger than the sum of its proper divisors (23746911).

71240721 is a wasteful number, since it uses less digits than its factorization.

71240721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23746910.

The product of its (nonzero) digits is 784, while the sum is 24.

The square root of 71240721 is about 8440.4218496471. The cubic root of 71240721 is about 414.5492197301.

Adding to 71240721 its reverse (12704217), we get a palindrome (83944938).

The spelling of 71240721 in words is "seventy-one million, two hundred forty thousand, seven hundred twenty-one".