2157809129 has 6 divisors (see below), whose sum is σ = 2510104554. Its totient is φ = 1849550640.

The previous prime is 2157809111. The next prime is 2157809141. The reversal of 2157809129 is 9219087512.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 2147395600 + 10413529 = 46340^2 + 3227^2 .

It is a de Polignac number, because none of the positive numbers 2^k-2157809129 is a prime.

It is a super-2 number, since 2×2157809129² = 9312280474391477282, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 2157809129.

It is not an unprimeable number, because it can be changed into a prime (2157809149) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 22018412 + ... + 22018509.

It is an arithmetic number, because the mean of its divisors is an integer number (418350759).

Almost surely, 2^2157809129 is an apocalyptic number.

It is an amenable number.

2157809129 is a deficient number, since it is larger than the sum of its proper divisors (352295425).

2157809129 is an equidigital number, since it uses as much as digits as its factorization.

2157809129 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 44036935 (or 44036928 counting only the distinct ones).

The product of its (nonzero) digits is 90720, while the sum is 44.

The square root of 2157809129 is about 46452.2241555773. The cubic root of 2157809129 is about 1292.2236209420.

The spelling of 2157809129 in words is "two billion, one hundred fifty-seven million, eight hundred nine thousand, one hundred twenty-nine".