5251978821 has 4 divisors (see below), whose sum is σ = 7002638432. Its totient is φ = 3501319212.

The previous prime is 5251978819. The next prime is 5251978877. The reversal of 5251978821 is 1288791525.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 5251978821 - 2¹ = 5251978819 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (5251978321) 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, 875329801 + ... + 875329806.

It is an arithmetic number, because the mean of its divisors is an integer number (1750659608).

Almost surely, 2^5251978821 is an apocalyptic number.

It is an amenable number.

5251978821 is a deficient number, since it is larger than the sum of its proper divisors (1750659611).

5251978821 is a wasteful number, since it uses less digits than its factorization.

5251978821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1750659610.

The product of its digits is 403200, while the sum is 48.

The square root of 5251978821 is about 72470.5376066716. The cubic root of 5251978821 is about 1738.2316580146.

The spelling of 5251978821 in words is "five billion, two hundred fifty-one million, nine hundred seventy-eight thousand, eight hundred twenty-one".