7821542728 has 8 divisors (see below), whose sum is σ = 14665392630. Its totient is φ = 3910771360.

The previous prime is 7821542713. The next prime is 7821542737. The reversal of 7821542728 is 8272451287.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 4976173764 + 2845368964 = 70542^2 + 53342^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is a super-2 number, since 2×7821542728² (a number of 21 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 488846413 + ... + 488846428.

Almost surely, 2^7821542728 is an apocalyptic number.

It is an amenable number.

7821542728 is a deficient number, since it is larger than the sum of its proper divisors (6843849902).

7821542728 is a wasteful number, since it uses less digits than its factorization.

7821542728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 977692847 (or 977692843 counting only the distinct ones).

The product of its digits is 501760, while the sum is 46.

The square root of 7821542728 is about 88439.4862490732. The cubic root of 7821542728 is about 1985.0165896923.

The spelling of 7821542728 in words is "seven billion, eight hundred twenty-one million, five hundred forty-two thousand, seven hundred twenty-eight".