71512021 has 6 divisors (see below), whose sum is σ = 83187510. Its totient is φ = 61295976.

The previous prime is 71512003. The next prime is 71512031. The reversal of 71512021 is 12021517.

It can be written as a sum of positive squares in only one way, i.e., 59505796 + 12006225 = 7714^2 + 3465^2 .

It is not a de Polignac number, because 71512021 - 2⁹ = 71511509 is a prime.

It is a super-2 number, since 2×71512021² = 10227938295008882, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 71512021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (71512031) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 729666 + ... + 729763.

It is an arithmetic number, because the mean of its divisors is an integer number (13864585).

Almost surely, 2^71512021 is an apocalyptic number.

It is an amenable number.

71512021 is a deficient number, since it is larger than the sum of its proper divisors (11675489).

71512021 is a wasteful number, since it uses less digits than its factorization.

71512021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1459443 (or 1459436 counting only the distinct ones).

The product of its (nonzero) digits is 140, while the sum is 19.

The square root of 71512021 is about 8456.4780494009. The cubic root of 71512021 is about 415.0747840262.

Adding to 71512021 its reverse (12021517), we get a palindrome (83533538).

The spelling of 71512021 in words is "seventy-one million, five hundred twelve thousand, twenty-one".