71157721 has 4 divisors (see below), whose sum is σ = 71212672. Its totient is φ = 71102772.

The previous prime is 71157703. The next prime is 71157727. The reversal of 71157721 is 12775117.

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, and also an emirpimes, since its reverse is a distinct semiprime: 12775117 = 47 ⋅271811.

It is a cyclic number.

It is not a de Polignac number, because 71157721 - 2⁹ = 71157209 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (71157727) 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, 25485 + ... + 28138.

It is an arithmetic number, because the mean of its divisors is an integer number (17803168).

Almost surely, 2^71157721 is an apocalyptic number.

It is an amenable number.

71157721 is a deficient number, since it is larger than the sum of its proper divisors (54951).

71157721 is a wasteful number, since it uses less digits than its factorization.

71157721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 54950.

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

The square root of 71157721 is about 8435.5036008528. The cubic root of 71157721 is about 414.3881650423.

The spelling of 71157721 in words is "seventy-one million, one hundred fifty-seven thousand, seven hundred twenty-one".