47809721 has 4 divisors (see below), whose sum is σ = 47855844. Its totient is φ = 47763600.

The previous prime is 47809717. The next prime is 47809753. The reversal of 47809721 is 12790874.

47809721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12790874 = 2 ⋅6395437.

It can be written as a sum of positive squares in 2 ways, for example, as 38440000 + 9369721 = 6200^2 + 3061^2 .

It is a cyclic number.

It is not a de Polignac number, because 47809721 - 2² = 47809717 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (47809711) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 21470 + ... + 23591.

It is an arithmetic number, because the mean of its divisors is an integer number (11963961).

Almost surely, 2^47809721 is an apocalyptic number.

It is an amenable number.

47809721 is a deficient number, since it is larger than the sum of its proper divisors (46123).

47809721 is a wasteful number, since it uses less digits than its factorization.

47809721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 46122.

The product of its (nonzero) digits is 28224, while the sum is 38.

The square root of 47809721 is about 6914.4573901355. The cubic root of 47809721 is about 362.9432605400.

The spelling of 47809721 in words is "forty-seven million, eight hundred nine thousand, seven hundred twenty-one".