2157665123 has 4 divisors (see below), whose sum is σ = 2171954448. Its totient is φ = 2143375800.

The previous prime is 2157665117. The next prime is 2157665149. The reversal of 2157665123 is 3215667512.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 2157665123 - 2⁸ = 2157664867 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2157665113) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7144436 + ... + 7144737.

It is an arithmetic number, because the mean of its divisors is an integer number (542988612).

Almost surely, 2^2157665123 is an apocalyptic number.

2157665123 is a deficient number, since it is larger than the sum of its proper divisors (14289325).

2157665123 is a wasteful number, since it uses less digits than its factorization.

2157665123 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14289324.

The product of its digits is 75600, while the sum is 38.

The square root of 2157665123 is about 46450.6740855286. The cubic root of 2157665123 is about 1292.1948738682.

The spelling of 2157665123 in words is "two billion, one hundred fifty-seven million, six hundred sixty-five thousand, one hundred twenty-three".