51078721 has 4 divisors (see below), whose sum is σ = 51101632. Its totient is φ = 51055812.

The previous prime is 51078701. The next prime is 51078733. The reversal of 51078721 is 12787015.

It is a happy number.

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 51078721 - 2¹¹ = 51076673 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (51078701) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7701 + ... + 12706.

It is an arithmetic number, because the mean of its divisors is an integer number (12775408).

Almost surely, 2^51078721 is an apocalyptic number.

It is an amenable number.

51078721 is a deficient number, since it is larger than the sum of its proper divisors (22911).

51078721 is a wasteful number, since it uses less digits than its factorization.

51078721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22910.

The product of its (nonzero) digits is 3920, while the sum is 31.

The square root of 51078721 is about 7146.9378757619. The cubic root of 51078721 is about 371.0336836097.

The spelling of 51078721 in words is "fifty-one million, seventy-eight thousand, seven hundred twenty-one".