161721106065500 has 48 divisors (see below), whose sum is σ = 353206204478400. Its totient is φ = 64687103812800.

The previous prime is 161721106065349. The next prime is 161721106065509. The reversal of 161721106065500 is 5560601127161.

It is a super-2 number, since 2×161721106065500² (a number of 29 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161721106065509) 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 15 ways as a sum of consecutive naturals, for example, 21017306 + ... + 27661694.

It is an arithmetic number, because the mean of its divisors is an integer number (7358462593300).

Almost surely, 2^{161721106065500} is an apocalyptic number.

161721106065500 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

161721106065500 is an abundant number, since it is smaller than the sum of its proper divisors (191485098412900).

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

161721106065500 is a wasteful number, since it uses less digits than its factorization.

161721106065500 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6693087 (or 6693075 counting only the distinct ones).

The product of its (nonzero) digits is 75600, while the sum is 41.

The spelling of 161721106065500 in words is "one hundred sixty-one trillion, seven hundred twenty-one billion, one hundred six million, sixty-five thousand, five hundred".