51387971 has 4 divisors (see below), whose sum is σ = 53160000. Its totient is φ = 49615944.

The previous prime is 51387961. The next prime is 51388019. The reversal of 51387971 is 17978315.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 17978315 = 5 ⋅3595663.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-51387971 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (51387961) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 885971 + ... + 886028.

It is an arithmetic number, because the mean of its divisors is an integer number (13290000).

Almost surely, 2^51387971 is an apocalyptic number.

51387971 is a deficient number, since it is larger than the sum of its proper divisors (1772029).

51387971 is a wasteful number, since it uses less digits than its factorization.

51387971 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1772028.

The product of its digits is 52920, while the sum is 41.

The square root of 51387971 is about 7168.5403674667. The cubic root of 51387971 is about 371.7809705159.

The spelling of 51387971 in words is "fifty-one million, three hundred eighty-seven thousand, nine hundred seventy-one".