51305681 has 24 divisors (see below), whose sum is σ = 62910720. Its totient is φ = 40974336.

The previous prime is 51305671. The next prime is 51305687. The reversal of 51305681 is 18650315.

It is not a de Polignac number, because 51305681 - 2¹⁴ = 51289297 is a prime.

It is a super-2 number, since 2×51305681² = 5264545805747522, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51305687) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 199505 + ... + 199761.

It is an arithmetic number, because the mean of its divisors is an integer number (2621280).

Almost surely, 2^51305681 is an apocalyptic number.

It is an amenable number.

51305681 is a deficient number, since it is larger than the sum of its proper divisors (11605039).

51305681 is a wasteful number, since it uses less digits than its factorization.

51305681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 381 (or 362 counting only the distinct ones).

The product of its (nonzero) digits is 3600, while the sum is 29.

The square root of 51305681 is about 7162.7984056512. The cubic root of 51305681 is about 371.5824143138.

Adding to 51305681 its reverse (18650315), we get a palindrome (69955996).

The spelling of 51305681 in words is "fifty-one million, three hundred five thousand, six hundred eighty-one".