161720155 has 16 divisors (see below), whose sum is σ = 200860704. Its totient is φ = 124899840.

The previous prime is 161720147. The next prime is 161720177. The reversal of 161720155 is 551027161.

It is not a de Polignac number, because 161720155 - 2³ = 161720147 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 20899 + ... + 27571.

It is an arithmetic number, because the mean of its divisors is an integer number (12553794).

Almost surely, 2^161720155 is an apocalyptic number.

161720155 is a deficient number, since it is larger than the sum of its proper divisors (39140549).

161720155 is a wasteful number, since it uses less digits than its factorization.

161720155 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6846.

The product of its (nonzero) digits is 2100, while the sum is 28.

The square root of 161720155 is about 12716.9239598261. The cubic root of 161720155 is about 544.8221005648.

The spelling of 161720155 in words is "one hundred sixty-one million, seven hundred twenty thousand, one hundred fifty-five".