2051721851868 has 36 divisors (see below), whose sum is σ = 5585242820248. Its totient is φ = 631299031200.

The previous prime is 2051721851843. The next prime is 2051721851899. The reversal of 2051721851868 is 8681581271502.

It is a happy number.

2051721851868 is a `hidden beast` number, since 2 + 0 + 51 + 7 + 2 + 18 + 518 + 68 = 666.

It is a tau number, because it is divible by the number of its divisors (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2192010058 + ... + 2192010993.

Almost surely, 2^{2051721851868} is an apocalyptic number.

It is an amenable number.

2051721851868 is an abundant number, since it is smaller than the sum of its proper divisors (3533520968380).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

2051721851868 is a wasteful number, since it uses less digits than its factorization.

2051721851868 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4384021074 (or 4384021069 counting only the distinct ones).

The product of its (nonzero) digits is 2150400, while the sum is 54.

The spelling of 2051721851868 in words is "two trillion, fifty-one billion, seven hundred twenty-one million, eight hundred fifty-one thousand, eight hundred sixty-eight".