51375721 has 16 divisors (see below), whose sum is σ = 55880064. Its totient is φ = 47101824.

The previous prime is 51375707. The next prime is 51375749. The reversal of 51375721 is 12757315.

It is a cyclic number.

It is not a de Polignac number, because 51375721 - 2⁵ = 51375689 is a prime.

It is not an unprimeable number, because it can be changed into a prime (51375781) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 61710 + ... + 62536.

It is an arithmetic number, because the mean of its divisors is an integer number (3492504).

Almost surely, 2^51375721 is an apocalyptic number.

It is an amenable number.

51375721 is a deficient number, since it is larger than the sum of its proper divisors (4504343).

51375721 is a wasteful number, since it uses less digits than its factorization.

51375721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 960.

The product of its digits is 7350, while the sum is 31.

The square root of 51375721 is about 7167.6858887649. The cubic root of 51375721 is about 371.7514261255.

The spelling of 51375721 in words is "fifty-one million, three hundred seventy-five thousand, seven hundred twenty-one".