51287391 has 16 divisors (see below), whose sum is σ = 77025120. Its totient is φ = 33721920.

The previous prime is 51287377. The next prime is 51287429. The reversal of 51287391 is 19378215.

It is not a de Polignac number, because 51287391 - 2⁵ = 51287359 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51287371) 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, 11040 + ... + 14981.

It is an arithmetic number, because the mean of its divisors is an integer number (4814070).

Almost surely, 2^51287391 is an apocalyptic number.

51287391 is a deficient number, since it is larger than the sum of its proper divisors (25737729).

51287391 is a wasteful number, since it uses less digits than its factorization.

51287391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26103 (or 26097 counting only the distinct ones).

The product of its digits is 15120, while the sum is 36.

The square root of 51287391 is about 7161.5215562058. The cubic root of 51287391 is about 371.5382538362.

The spelling of 51287391 in words is "fifty-one million, two hundred eighty-seven thousand, three hundred ninety-one".