71723021 has 4 divisors (see below), whose sum is σ = 72357852. Its totient is φ = 71088192.

The previous prime is 71723009. The next prime is 71723033. The reversal of 71723021 is 12032717.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (71723009) and next prime (71723033).

It can be written as a sum of positive squares in 2 ways, for example, as 21114025 + 50608996 = 4595^2 + 7114^2 .

It is a cyclic number.

It is not a de Polignac number, because 71723021 - 2¹⁴ = 71706637 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (71723921) 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, 317246 + ... + 317471.

It is an arithmetic number, because the mean of its divisors is an integer number (18089463).

Almost surely, 2^71723021 is an apocalyptic number.

It is an amenable number.

71723021 is a deficient number, since it is larger than the sum of its proper divisors (634831).

71723021 is a wasteful number, since it uses less digits than its factorization.

71723021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 634830.

The product of its (nonzero) digits is 588, while the sum is 23.

The square root of 71723021 is about 8468.9445033015. The cubic root of 71723021 is about 415.4826165457.

Adding to 71723021 its reverse (12032717), we get a palindrome (83755738).

It can be divided in two parts, 7172 and 3021, that multiplied together give a palindrome (21666612).

The spelling of 71723021 in words is "seventy-one million, seven hundred twenty-three thousand, twenty-one".