261386143605172 has 6 divisors (see below), whose sum is σ = 457425751309058. Its totient is φ = 130693071802584.

The previous prime is 261386143605161. The next prime is 261386143605187. The reversal of 261386143605172 is 271506341683162.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 186508896394276 + 74877247210896 = 13656826^2 + 8653164^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 32673267950643 + ... + 32673267950650.

Almost surely, 2^{261386143605172} is an apocalyptic number.

It is an amenable number.

261386143605172 is a deficient number, since it is larger than the sum of its proper divisors (196039607703886).

261386143605172 is a wasteful number, since it uses less digits than its factorization.

261386143605172 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 65346535901297 (or 65346535901295 counting only the distinct ones).

The product of its (nonzero) digits is 8709120, while the sum is 55.

The spelling of 261386143605172 in words is "two hundred sixty-one trillion, three hundred eighty-six billion, one hundred forty-three million, six hundred five thousand, one hundred seventy-two".