161645551405 has 8 divisors (see below), whose sum is σ = 208895789592. Its totient is φ = 119369022528.

The previous prime is 161645551393. The next prime is 161645551409. The reversal of 161645551405 is 504155546161.

It can be written as a sum of positive squares in 4 ways, for example, as 578979844 + 161066571561 = 24062^2 + 401331^2 .

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-161645551405 is a prime.

It is a super-2 number, since 2×161645551405² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161645551409) 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, 1243427254 + ... + 1243427383.

It is an arithmetic number, because the mean of its divisors is an integer number (26111973699).

Almost surely, 2^161645551405 is an apocalyptic number.

It is an amenable number.

161645551405 is a deficient number, since it is larger than the sum of its proper divisors (47250238187).

161645551405 is a wasteful number, since it uses less digits than its factorization.

161645551405 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2486854655.

The product of its (nonzero) digits is 360000, while the sum is 43.

The spelling of 161645551405 in words is "one hundred sixty-one billion, six hundred forty-five million, five hundred fifty-one thousand, four hundred five".