201561512172 has 12 divisors (see below), whose sum is σ = 470310195096. Its totient is φ = 67187170720.

The previous prime is 201561512171. The next prime is 201561512239. The reversal of 201561512172 is 271215165102.

It is a tau number, because it is divible by the number of its divisors (12).

It is not an unprimeable number, because it can be changed into a prime (201561512171) 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, 8398396329 + ... + 8398396352.

It is an arithmetic number, because the mean of its divisors is an integer number (39192516258).

Almost surely, 2^201561512172 is an apocalyptic number.

It is an amenable number.

201561512172 is an abundant number, since it is smaller than the sum of its proper divisors (268748682924).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

201561512172 is a wasteful number, since it uses less digits than its factorization.

201561512172 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16796792688 (or 16796792686 counting only the distinct ones).

The product of its (nonzero) digits is 8400, while the sum is 33.

Adding to 201561512172 its reverse (271215165102), we get a palindrome (472776677274).

The spelling of 201561512172 in words is "two hundred one billion, five hundred sixty-one million, five hundred twelve thousand, one hundred seventy-two".