51139985 has 12 divisors (see below), whose sum is σ = 66163188. Its totient is φ = 37722336.

The previous prime is 51139981. The next prime is 51139999. The reversal of 51139985 is 58993115.

It can be written as a sum of positive squares in 2 ways, for example, as 12588304 + 38551681 = 3548^2 + 6209^2 .

It is not a de Polignac number, because 51139985 - 2² = 51139981 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51139981) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 57212 + ... + 58098.

It is an arithmetic number, because the mean of its divisors is an integer number (5513599).

Almost surely, 2^51139985 is an apocalyptic number.

It is an amenable number.

51139985 is a deficient number, since it is larger than the sum of its proper divisors (15023203).

51139985 is an frugal number, since it uses more digits than its factorization.

51139985 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1792 (or 905 counting only the distinct ones).

The product of its digits is 48600, while the sum is 41.

The square root of 51139985 is about 7151.2226227408. Note that the first 3 decimals coincide. The cubic root of 51139985 is about 371.1819640503.

The spelling of 51139985 in words is "fifty-one million, one hundred thirty-nine thousand, nine hundred eighty-five".