7185728821 has 4 divisors (see below), whose sum is σ = 7186214700. Its totient is φ = 7185242944.

The previous prime is 7185728801. The next prime is 7185728897. The reversal of 7185728821 is 1288275817.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1288275817 = 1823 ⋅706679.

It can be written as a sum of positive squares in 2 ways, for example, as 3596400900 + 3589327921 = 59970^2 + 59911^2 .

It is a cyclic number.

It is not a de Polignac number, because 7185728821 - 2⁵ = 7185728789 is a prime.

It is a Smith number, since the sum of its digits (49) 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 a congruent number.

It is not an unprimeable number, because it can be changed into a prime (7185728801) 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, 220036 + ... + 250573.

It is an arithmetic number, because the mean of its divisors is an integer number (1796553675).

Almost surely, 2^7185728821 is an apocalyptic number.

It is an amenable number.

7185728821 is a deficient number, since it is larger than the sum of its proper divisors (485879).

7185728821 is a wasteful number, since it uses less digits than its factorization.

7185728821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 485878.

The product of its digits is 501760, while the sum is 49.

The square root of 7185728821 is about 84768.6783015991. The cubic root of 7185728821 is about 1929.7021224081.

The spelling of 7185728821 in words is "seven billion, one hundred eighty-five million, seven hundred twenty-eight thousand, eight hundred twenty-one".