157721105 has 4 divisors (see below), whose sum is σ = 189265332. Its totient is φ = 126176880.

The previous prime is 157721089. The next prime is 157721107. The reversal of 157721105 is 501127751.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 501127751 = 17 ⋅29478103.

It can be written as a sum of positive squares in 2 ways, for example, as 122389969 + 35331136 = 11063^2 + 5944^2 .

It is not a de Polignac number, because 157721105 - 2⁴ = 157721089 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (157721107) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 15772106 + ... + 15772115.

It is an arithmetic number, because the mean of its divisors is an integer number (47316333).

Almost surely, 2^157721105 is an apocalyptic number.

It is an amenable number.

157721105 is a deficient number, since it is larger than the sum of its proper divisors (31544227).

157721105 is an equidigital number, since it uses as much as digits as its factorization.

157721105 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31544226.

The product of its (nonzero) digits is 2450, while the sum is 29.

The square root of 157721105 is about 12558.7063426135. The cubic root of 157721105 is about 540.2937416487.

Adding to 157721105 its reverse (501127751), we get a palindrome (658848856).

The spelling of 157721105 in words is "one hundred fifty-seven million, seven hundred twenty-one thousand, one hundred five".