51866991 has 48 divisors (see below), whose sum is σ = 85183488. Its totient is φ = 30139200.

The previous prime is 51866981. The next prime is 51867031. The reversal of 51866991 is 19966815.

It is not a de Polignac number, because 51866991 - 2¹⁴ = 51850607 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51866921) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 330285 + ... + 330441.

It is an arithmetic number, because the mean of its divisors is an integer number (1774656).

Almost surely, 2^51866991 is an apocalyptic number.

51866991 is a deficient number, since it is larger than the sum of its proper divisors (33316497).

51866991 is a wasteful number, since it uses less digits than its factorization.

51866991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 292 (or 289 counting only the distinct ones).

The product of its digits is 116640, while the sum is 45.

The square root of 51866991 is about 7201.8741310856. The cubic root of 51866991 is about 372.9326019192.

The spelling of 51866991 in words is "fifty-one million, eight hundred sixty-six thousand, nine hundred ninety-one".