72171655209 has 40 divisors (see below), whose sum is σ = 108383692032. Its totient is φ = 47859776640.

The previous prime is 72171655207. The next prime is 72171655271. The reversal of 72171655209 is 90255617127.

72171655209 is a `hidden beast` number, since 7 + 21 + 71 + 6 + 552 + 0 + 9 = 666.

It is not a de Polignac number, because 72171655209 - 2¹ = 72171655207 is a prime.

It is not an unprimeable number, because it can be changed into a prime (72171655201) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 23872672 + ... + 23875694.

Almost surely, 2^72171655209 is an apocalyptic number.

It is an amenable number.

72171655209 is a deficient number, since it is larger than the sum of its proper divisors (36212036823).

72171655209 is a wasteful number, since it uses less digits than its factorization.

72171655209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4499 (or 4490 counting only the distinct ones).

The product of its (nonzero) digits is 264600, while the sum is 45.

The spelling of 72171655209 in words is "seventy-two billion, one hundred seventy-one million, six hundred fifty-five thousand, two hundred nine".