2123551817 has 4 divisors (see below), whose sum is σ = 2123991060. Its totient is φ = 2123112576.

The previous prime is 2123551811. The next prime is 2123551831. The reversal of 2123551817 is 7181553212.

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 1847194441 + 276357376 = 42979^2 + 16624^2 .

It is a cyclic number.

It is not a de Polignac number, because 2123551817 - 2¹² = 2123547721 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2123551811) 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, 212288 + ... + 222065.

It is an arithmetic number, because the mean of its divisors is an integer number (530997765).

Almost surely, 2^2123551817 is an apocalyptic number.

It is an amenable number.

2123551817 is a deficient number, since it is larger than the sum of its proper divisors (439243).

2123551817 is an equidigital number, since it uses as much as digits as its factorization.

2123551817 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 439242.

The product of its digits is 16800, while the sum is 35.

The square root of 2123551817 is about 46082.0118592928. The cubic root of 2123551817 is about 1285.3486751328.

The spelling of 2123551817 in words is "two billion, one hundred twenty-three million, five hundred fifty-one thousand, eight hundred seventeen".