71248721 has 4 divisors (see below), whose sum is σ = 72905712. Its totient is φ = 69591732.

The previous prime is 71248711. The next prime is 71248739. The reversal of 71248721 is 12784217.

It is a happy number.

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 a de Polignac number, because none of the positive numbers 2^k-71248721 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (71248711) 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, 828431 + ... + 828516.

It is an arithmetic number, because the mean of its divisors is an integer number (18226428).

Almost surely, 2^71248721 is an apocalyptic number.

It is an amenable number.

71248721 is a deficient number, since it is larger than the sum of its proper divisors (1656991).

71248721 is a wasteful number, since it uses less digits than its factorization.

71248721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1656990.

The product of its digits is 6272, while the sum is 32.

The square root of 71248721 is about 8440.8957463056. The cubic root of 71248721 is about 414.5647364626.

The spelling of 71248721 in words is "seventy-one million, two hundred forty-eight thousand, seven hundred twenty-one".