71511721 has 8 divisors (see below), whose sum is σ = 72936864. Its totient is φ = 70100160.

The previous prime is 71511719. The next prime is 71511733. The reversal of 71511721 is 12711517.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 71511721 - 2¹ = 71511719 is a prime.

It is a super-2 number, since 2×71511721² = 10227852480763682, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (71511221) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7585 + ... + 14161.

It is an arithmetic number, because the mean of its divisors is an integer number (9117108).

Almost surely, 2^71511721 is an apocalyptic number.

It is an amenable number.

71511721 is a deficient number, since it is larger than the sum of its proper divisors (1425143).

71511721 is a wasteful number, since it uses less digits than its factorization.

71511721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6791.

The product of its digits is 490, while the sum is 25.

The square root of 71511721 is about 8456.4603115015. The cubic root of 71511721 is about 415.0742035988.

The spelling of 71511721 in words is "seventy-one million, five hundred eleven thousand, seven hundred twenty-one".