2175728251 has 4 divisors (see below), whose sum is σ = 2175831504. Its totient is φ = 2175625000.

The previous prime is 2175728239. The next prime is 2175728257. The reversal of 2175728251 is 1528275712.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a 3-Lehmer number, since φ(2175728251) divides (2175728251-1)³.

It is a cyclic number.

It is not a de Polignac number, because 2175728251 - 2⁷ = 2175728123 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2175728257) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7375 + ... + 66376.

It is an arithmetic number, because the mean of its divisors is an integer number (543957876).

Almost surely, 2^2175728251 is an apocalyptic number.

2175728251 is the 29501-st heptagonal number.

2175728251 is a deficient number, since it is larger than the sum of its proper divisors (103253).

2175728251 is an equidigital number, since it uses as much as digits as its factorization.

2175728251 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 103252.

The product of its digits is 78400, while the sum is 40.

The square root of 2175728251 is about 46644.7022822528. The cubic root of 2175728251 is about 1295.7907745601.

The spelling of 2175728251 in words is "two billion, one hundred seventy-five million, seven hundred twenty-eight thousand, two hundred fifty-one".