72171071831 has 4 divisors (see below), whose sum is σ = 72288043392. Its totient is φ = 72054100272.

The previous prime is 72171071813. The next prime is 72171071849. The reversal of 72171071831 is 13817017127.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 13817017127 = 251 ⋅55047877.

It is an interprime number because it is at equal distance from previous prime (72171071813) and next prime (72171071849).

It is a cyclic number.

It is not a de Polignac number, because 72171071831 - 2³⁴ = 54991202647 is a prime.

It is a super-2 number, since 2×72171071831² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (72171071881) 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, 58484855 + ... + 58486088.

It is an arithmetic number, because the mean of its divisors is an integer number (18072010848).

Almost surely, 2^72171071831 is an apocalyptic number.

72171071831 is a deficient number, since it is larger than the sum of its proper divisors (116971561).

72171071831 is a wasteful number, since it uses less digits than its factorization.

72171071831 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 116971560.

The product of its (nonzero) digits is 16464, while the sum is 38.

Adding to 72171071831 its reverse (13817017127), we get a palindrome (85988088958).

The spelling of 72171071831 in words is "seventy-two billion, one hundred seventy-one million, seventy-one thousand, eight hundred thirty-one".