161555645225 has 24 divisors (see below), whose sum is σ = 219395541120. Its totient is φ = 117280537920.

The previous prime is 161555645219. The next prime is 161555645227. The reversal of 161555645225 is 522546555161.

It is not a de Polignac number, because 161555645225 - 2⁸ = 161555644969 is a prime.

It is a super-2 number, since 2×161555645225² (a number of 23 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 161555645225.

It is not an unprimeable number, because it can be changed into a prime (161555645227) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 4193489 + ... + 4231838.

It is an arithmetic number, because the mean of its divisors is an integer number (9141480880).

Almost surely, 2^161555645225 is an apocalyptic number.

It is an amenable number.

161555645225 is a deficient number, since it is larger than the sum of its proper divisors (57839895895).

161555645225 is a wasteful number, since it uses less digits than its factorization.

161555645225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8425409 (or 8425404 counting only the distinct ones).

The product of its digits is 1800000, while the sum is 47.

The spelling of 161555645225 in words is "one hundred sixty-one billion, five hundred fifty-five million, six hundred forty-five thousand, two hundred twenty-five".