71388021 has 12 divisors (see below), whose sum is σ = 99504608. Its totient is φ = 45521784.

The previous prime is 71388019. The next prime is 71388047. The reversal of 71388021 is 12088317.

It is a happy number.

It is not a de Polignac number, because 71388021 - 2¹ = 71388019 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 71388021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (71388001) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 20905 + ... + 24078.

Almost surely, 2^71388021 is an apocalyptic number.

It is an amenable number.

71388021 is a deficient number, since it is larger than the sum of its proper divisors (28116587).

71388021 is a wasteful number, since it uses less digits than its factorization.

71388021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 45032 (or 45009 counting only the distinct ones).

The product of its (nonzero) digits is 2688, while the sum is 30.

The square root of 71388021 is about 8449.1432110007. The cubic root of 71388021 is about 414.8347355701.

The spelling of 71388021 in words is "seventy-one million, three hundred eighty-eight thousand, twenty-one".