161257688221 has 24 divisors (see below), whose sum is σ = 191897064576. Its totient is φ = 135053755200.

The previous prime is 161257688213. The next prime is 161257688243. The reversal of 161257688221 is 122886752161.

161257688221 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 161257688221 - 2³ = 161257688213 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (49).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161257683221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1325850 + ... + 1442356.

It is an arithmetic number, because the mean of its divisors is an integer number (7995711024).

Almost surely, 2^161257688221 is an apocalyptic number.

It is an amenable number.

161257688221 is a deficient number, since it is larger than the sum of its proper divisors (30639376355).

161257688221 is a wasteful number, since it uses less digits than its factorization.

161257688221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 117169 (or 117162 counting only the distinct ones).

The product of its digits is 645120, while the sum is 49.

The spelling of 161257688221 in words is "one hundred sixty-one billion, two hundred fifty-seven million, six hundred eighty-eight thousand, two hundred twenty-one".