161621556605 has 8 divisors (see below), whose sum is σ = 194334540000. Its totient is φ = 129038130576.

The previous prime is 161621556601. The next prime is 161621556617. The reversal of 161621556605 is 506655126161.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 161621556605 - 2² = 161621556601 is a prime.

It is a super-3 number, since 3×161621556605³ (a number of 35 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161621556601) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 32386595 + ... + 32391584.

It is an arithmetic number, because the mean of its divisors is an integer number (24291817500).

Almost surely, 2^161621556605 is an apocalyptic number.

It is an amenable number.

161621556605 is a deficient number, since it is larger than the sum of its proper divisors (32712983395).

161621556605 is an equidigital number, since it uses as much as digits as its factorization.

161621556605 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 64778683.

The product of its (nonzero) digits is 324000, while the sum is 44.

The spelling of 161621556605 in words is "one hundred sixty-one billion, six hundred twenty-one million, five hundred fifty-six thousand, six hundred five".