72171523 has 4 divisors (see below), whose sum is σ = 73160248. Its totient is φ = 71182800.

The previous prime is 72171457. The next prime is 72171527. The reversal of 72171523 is 32517127.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 32517127 = 1669 ⋅19483.

It is a cyclic number.

It is not a de Polignac number, because 72171523 - 2²⁵ = 38617091 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 72171491 and 72171500.

It is not an unprimeable number, because it can be changed into a prime (72171527) 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, 494253 + ... + 494398.

It is an arithmetic number, because the mean of its divisors is an integer number (18290062).

Almost surely, 2^72171523 is an apocalyptic number.

72171523 is a gapful number since it is divisible by the number (73) formed by its first and last digit.

72171523 is a deficient number, since it is larger than the sum of its proper divisors (988725).

72171523 is an equidigital number, since it uses as much as digits as its factorization.

72171523 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 988724.

The product of its digits is 2940, while the sum is 28.

The square root of 72171523 is about 8495.3824516616. The cubic root of 72171523 is about 416.3468565321.

The spelling of 72171523 in words is "seventy-two million, one hundred seventy-one thousand, five hundred twenty-three".