2081721851 has 4 divisors (see below), whose sum is σ = 2270969304. Its totient is φ = 1892474400.

The previous prime is 2081721799. The next prime is 2081721857. The reversal of 2081721851 is 1581271802.

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 2081721851 - 2¹⁴ = 2081705467 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2081721857) 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, 94623710 + ... + 94623731.

It is an arithmetic number, because the mean of its divisors is an integer number (567742326).

Almost surely, 2^2081721851 is an apocalyptic number.

2081721851 is a deficient number, since it is larger than the sum of its proper divisors (189247453).

2081721851 is a wasteful number, since it uses less digits than its factorization.

2081721851 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 189247452.

The product of its (nonzero) digits is 8960, while the sum is 35.

The square root of 2081721851 is about 45625.8901392619. The cubic root of 2081721851 is about 1276.8529972824.

The spelling of 2081721851 in words is "two billion, eighty-one million, seven hundred twenty-one thousand, eight hundred fifty-one".