71306021 has 4 divisors (see below), whose sum is σ = 71323200. Its totient is φ = 71288844.

The previous prime is 71306017. The next prime is 71306029. The reversal of 71306021 is 12060317.

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, and also an emirpimes, since its reverse is a distinct semiprime: 12060317 = 29 ⋅415873.

It is a cyclic number.

It is not a de Polignac number, because 71306021 - 2² = 71306017 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 71305984 and 71306002.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (71306029) 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, 1940 + ... + 12098.

It is an arithmetic number, because the mean of its divisors is an integer number (17830800).

Almost surely, 2^71306021 is an apocalyptic number.

It is an amenable number.

71306021 is a deficient number, since it is larger than the sum of its proper divisors (17179).

71306021 is a wasteful number, since it uses less digits than its factorization.

71306021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17178.

The product of its (nonzero) digits is 252, while the sum is 20.

The square root of 71306021 is about 8444.2892536909. The cubic root of 71306021 is about 414.6758411201.

Adding to 71306021 its reverse (12060317), we get a palindrome (83366338).

The spelling of 71306021 in words is "seventy-one million, three hundred six thousand, twenty-one".