51987121 has 2 divisors, whose sum is σ = 51987122. Its totient is φ = 51987120.

The previous prime is 51987113. The next prime is 51987137. The reversal of 51987121 is 12178915.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 51322896 + 664225 = 7164^2 + 815^2 .

It is a cyclic number.

It is not a de Polignac number, because 51987121 - 2³ = 51987113 is a prime.

It is not a weakly prime, because it can be changed into another prime (51987151) 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 as a sum of consecutive naturals, namely, 25993560 + 25993561.

It is an arithmetic number, because the mean of its divisors is an integer number (25993561).

Almost surely, 2^51987121 is an apocalyptic number.

It is an amenable number.

51987121 is a deficient number, since it is larger than the sum of its proper divisors (1).

51987121 is an equidigital number, since it uses as much as digits as its factorization.

51987121 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5040, while the sum is 34.

The square root of 51987121 is about 7210.2094976498. The cubic root of 51987121 is about 373.2202983866.

The spelling of 51987121 in words is "fifty-one million, nine hundred eighty-seven thousand, one hundred twenty-one".