51256581 has 32 divisors (see below), whose sum is σ = 77614848. Its totient is φ = 29905920.

The previous prime is 51256577. The next prime is 51256589. The reversal of 51256581 is 18565215.

It is not a de Polignac number, because 51256581 - 2² = 51256577 is a prime.

It is a super-2 number, since 2×51256581² = 5254474191619122, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51256589) 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 31 ways as a sum of consecutive naturals, for example, 42811 + ... + 43991.

It is an arithmetic number, because the mean of its divisors is an integer number (2425464).

Almost surely, 2^51256581 is an apocalyptic number.

51256581 is a gapful number since it is divisible by the number (51) formed by its first and last digit.

It is an amenable number.

51256581 is a deficient number, since it is larger than the sum of its proper divisors (26358267).

51256581 is a wasteful number, since it uses less digits than its factorization.

51256581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1261.

The product of its digits is 12000, while the sum is 33.

The square root of 51256581 is about 7159.3701538613. The cubic root of 51256581 is about 371.4638405717.

The spelling of 51256581 in words is "fifty-one million, two hundred fifty-six thousand, five hundred eighty-one".