7821428557 has 32 divisors (see below), whose sum is σ = 8684282880. Its totient is φ = 7022453760.

The previous prime is 7821428521. The next prime is 7821428569. The reversal of 7821428557 is 7558241287.

It is a happy number.

7821428557 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a cyclic number.

It is not a de Polignac number, because 7821428557 - 2⁷ = 7821428429 is a prime.

It is a super-2 number, since 2×7821428557² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 7821428557.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (7821428597) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2759413 + ... + 2762245.

It is an arithmetic number, because the mean of its divisors is an integer number (271383840).

Almost surely, 2^7821428557 is an apocalyptic number.

It is an amenable number.

7821428557 is a deficient number, since it is larger than the sum of its proper divisors (862854323).

7821428557 is a wasteful number, since it uses less digits than its factorization.

7821428557 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3013.

The product of its digits is 1254400, while the sum is 49.

The square root of 7821428557 is about 88438.8407714619. The cubic root of 7821428557 is about 1985.0069312213.

The spelling of 7821428557 in words is "seven billion, eight hundred twenty-one million, four hundred twenty-eight thousand, five hundred fifty-seven".