51891640 has 32 divisors (see below), whose sum is σ = 117514080. Its totient is φ = 20621952.

The previous prime is 51891617. The next prime is 51891647. The reversal of 51891640 is 4619815.

It is a super-4 number, since 4×51891640⁴ (a number of 32 digits) contains 4444 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 51891596 and 51891605.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51891647) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2149 + ... + 10411.

It is an arithmetic number, because the mean of its divisors is an integer number (3672315).

Almost surely, 2^51891640 is an apocalyptic number.

It is an amenable number.

51891640 is an abundant number, since it is smaller than the sum of its proper divisors (65622440).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

51891640 is a wasteful number, since it uses less digits than its factorization.

51891640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8431 (or 8427 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 34.

The square root of 51891640 is about 7203.5852184867. The cubic root of 51891640 is about 372.9916694155.

The spelling of 51891640 in words is "fifty-one million, eight hundred ninety-one thousand, six hundred forty".