51045721 has 4 divisors (see below), whose sum is σ = 51351552. Its totient is φ = 50739892.

The previous prime is 51045719. The next prime is 51045733. The reversal of 51045721 is 12754015.

51045721 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 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 51045721 - 2¹ = 51045719 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (51045791) 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, 152665 + ... + 152998.

It is an arithmetic number, because the mean of its divisors is an integer number (12837888).

Almost surely, 2^51045721 is an apocalyptic number.

It is an amenable number.

51045721 is a deficient number, since it is larger than the sum of its proper divisors (305831).

51045721 is a wasteful number, since it uses less digits than its factorization.

51045721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 305830.

The product of its (nonzero) digits is 1400, while the sum is 25.

The square root of 51045721 is about 7144.6288217094. The cubic root of 51045721 is about 370.9537628581.

Adding to 51045721 its reverse (12754015), we get a palindrome (63799736).

The spelling of 51045721 in words is "fifty-one million, forty-five thousand, seven hundred twenty-one".