2157788305 has 4 divisors (see below), whose sum is σ = 2589345972. Its totient is φ = 1726230640.

The previous prime is 2157788299. The next prime is 2157788327. The reversal of 2157788305 is 5038877512.

It is a Cunningham number, because it is equal to 46452²+1.

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

It can be written as a sum of positive squares in 2 ways, for example, as 776848384 + 1380939921 = 27872^2 + 37161^2 .

It is not a de Polignac number, because 2157788305 - 2⁵ = 2157788273 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 215778826 + ... + 215778835.

It is an arithmetic number, because the mean of its divisors is an integer number (647336493).

Almost surely, 2^2157788305 is an apocalyptic number.

It is an amenable number.

2157788305 is a deficient number, since it is larger than the sum of its proper divisors (431557667).

2157788305 is an equidigital number, since it uses as much as digits as its factorization.

2157788305 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 431557666.

The product of its (nonzero) digits is 470400, while the sum is 46.

The square root of 2157788305 is about 46452.0000107638. Note that the first 4 decimals coincide. The cubic root of 2157788305 is about 1292.2194640480.

The spelling of 2157788305 in words is "two billion, one hundred fifty-seven million, seven hundred eighty-eight thousand, three hundred five".