51139921 has 12 divisors (see below), whose sum is σ = 59033856. Its totient is φ = 43396560.

The previous prime is 51139889. The next prime is 51139967. The reversal of 51139921 is 12993115.

It is a happy number.

It is not a de Polignac number, because 51139921 - 2⁵ = 51139889 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, 229216 + ... + 229438.

It is an arithmetic number, because the mean of its divisors is an integer number (4919488).

Almost surely, 2^51139921 is an apocalyptic number.

It is an amenable number.

51139921 is a deficient number, since it is larger than the sum of its proper divisors (7893935).

51139921 is an equidigital number, since it uses as much as digits as its factorization.

51139921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 592 (or 411 counting only the distinct ones).

The product of its digits is 2430, while the sum is 31.

The square root of 51139921 is about 7151.2181479801. The cubic root of 51139921 is about 371.1818092095.

The spelling of 51139921 in words is "fifty-one million, one hundred thirty-nine thousand, nine hundred twenty-one".