51399999 has 24 divisors (see below), whose sum is σ = 86661120. Its totient is φ = 28744848.

The previous prime is 51399979. The next prime is 51400001. The reversal of 51399999 is 99999315.

It is a happy number.

51399999 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a de Polignac number, because none of the positive numbers 2^k-51399999 is a prime.

51399999 is a modest number, since divided by 9999 gives 5139 as remainder.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51399979) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 5719 + ... + 11640.

It is an arithmetic number, because the mean of its divisors is an integer number (3610880).

Almost surely, 2^51399999 is an apocalyptic number.

51399999 is a deficient number, since it is larger than the sum of its proper divisors (35261121).

51399999 is a wasteful number, since it uses less digits than its factorization.

51399999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17419 (or 17416 counting only the distinct ones).

The product of its digits is 885735, while the sum is 54.

The square root of 51399999 is about 7169.3792618329. The cubic root of 51399999 is about 371.8099749215.

The spelling of 51399999 in words is "fifty-one million, three hundred ninety-nine thousand, nine hundred ninety-nine".