31720071 has 4 divisors (see below), whose sum is σ = 42293432. Its totient is φ = 21146712.

The previous prime is 31720049. The next prime is 31720103. The reversal of 31720071 is 17002713.

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

It is not a de Polignac number, because 31720071 - 2⁹ = 31719559 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 (31720771) 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, 5286676 + ... + 5286681.

It is an arithmetic number, because the mean of its divisors is an integer number (10573358).

Almost surely, 2^31720071 is an apocalyptic number.

31720071 is a deficient number, since it is larger than the sum of its proper divisors (10573361).

31720071 is a wasteful number, since it uses less digits than its factorization.

31720071 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10573360.

The product of its (nonzero) digits is 294, while the sum is 21.

The square root of 31720071 is about 5632.0574393378. The cubic root of 31720071 is about 316.5517486369.

Adding to 31720071 its reverse (17002713), we get a palindrome (48722784).

The spelling of 31720071 in words is "thirty-one million, seven hundred twenty thousand, seventy-one".