51333721 has 4 divisors (see below), whose sum is σ = 51448500. Its totient is φ = 51218944.

The previous prime is 51333719. The next prime is 51333731. The reversal of 51333721 is 12733315.

51333721 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.

It can be written as a sum of positive squares in 2 ways, for example, as 33177600 + 18156121 = 5760^2 + 4261^2 .

It is a cyclic number.

It is not a de Polignac number, because 51333721 - 2¹ = 51333719 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (51333731) 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, 56716 + ... + 57613.

It is an arithmetic number, because the mean of its divisors is an integer number (12862125).

Almost surely, 2^51333721 is an apocalyptic number.

It is an amenable number.

51333721 is a deficient number, since it is larger than the sum of its proper divisors (114779).

51333721 is a wasteful number, since it uses less digits than its factorization.

51333721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 114778.

The product of its digits is 1890, while the sum is 25.

The square root of 51333721 is about 7164.7554738456. The cubic root of 51333721 is about 371.6500954045.

The spelling of 51333721 in words is "fifty-one million, three hundred thirty-three thousand, seven hundred twenty-one".