51391243 has 2 divisors, whose sum is σ = 51391244. Its totient is φ = 51391242.

The previous prime is 51391231. The next prime is 51391271. The reversal of 51391243 is 34219315.

It is an a-pointer prime, because the next prime (51391271) can be obtained adding 51391243 to its sum of digits (28).

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-51391243 is a prime.

It is equal to p_3079540 and since 51391243 and 3079540 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (51391843) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25695621 + 25695622.

It is an arithmetic number, because the mean of its divisors is an integer number (25695622).

Almost surely, 2^51391243 is an apocalyptic number.

51391243 is a deficient number, since it is larger than the sum of its proper divisors (1).

51391243 is an equidigital number, since it uses as much as digits as its factorization.

51391243 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3240, while the sum is 28.

The square root of 51391243 is about 7168.7685832366. The cubic root of 51391243 is about 371.7888610883.

The spelling of 51391243 in words is "fifty-one million, three hundred ninety-one thousand, two hundred forty-three".