47979815821 has 4 divisors (see below), whose sum is σ = 54834075232. Its totient is φ = 41125556412.

The previous prime is 47979815791. The next prime is 47979815903. The reversal of 47979815821 is 12851897974.

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 a cyclic number.

It is not a de Polignac number, because 47979815821 - 2⁷ = 47979815693 is a prime.

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 47979815821.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (47979825821) 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, 3427129695 + ... + 3427129708.

It is an arithmetic number, because the mean of its divisors is an integer number (13708518808).

Almost surely, 2^47979815821 is an apocalyptic number.

It is an amenable number.

47979815821 is a deficient number, since it is larger than the sum of its proper divisors (6854259411).

47979815821 is an equidigital number, since it uses as much as digits as its factorization.

47979815821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6854259410.

The product of its digits is 10160640, while the sum is 61.

The spelling of 47979815821 in words is "forty-seven billion, nine hundred seventy-nine million, eight hundred fifteen thousand, eight hundred twenty-one".