51391639 has 8 divisors (see below), whose sum is σ = 55417040. Its totient is φ = 47376576.

The previous prime is 51391621. The next prime is 51391651. The reversal of 51391639 is 93619315.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a de Polignac number, because none of the positive numbers 2^k-51391639 is a prime.

It is a super-2 number, since 2×51391639² = 5282201118212642, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 51391598 and 51391607.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51391619) 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 7 ways as a sum of consecutive naturals, for example, 10072 + ... + 14290.

It is an arithmetic number, because the mean of its divisors is an integer number (6927130).

Almost surely, 2^51391639 is an apocalyptic number.

51391639 is a deficient number, since it is larger than the sum of its proper divisors (4025401).

51391639 is a wasteful number, since it uses less digits than its factorization.

51391639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5169.

The product of its digits is 21870, while the sum is 37.

The square root of 51391639 is about 7168.7962029897. The cubic root of 51391639 is about 371.7898160371.

The spelling of 51391639 in words is "fifty-one million, three hundred ninety-one thousand, six hundred thirty-nine".