51129281 has 4 divisors (see below), whose sum is σ = 58433472. Its totient is φ = 43825092.

The previous prime is 51129277. The next prime is 51129283. The reversal of 51129281 is 18292115.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 18292115 = 5 ⋅3658423.

It is a cyclic number.

It is not a de Polignac number, because 51129281 - 2² = 51129277 is a prime.

It is a super-2 number, since 2×51129281² = 5228406751153922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (51129283) 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 3 ways as a sum of consecutive naturals, for example, 3652085 + ... + 3652098.

It is an arithmetic number, because the mean of its divisors is an integer number (14608368).

Almost surely, 2^51129281 is an apocalyptic number.

It is an amenable number.

51129281 is a deficient number, since it is larger than the sum of its proper divisors (7304191).

51129281 is an equidigital number, since it uses as much as digits as its factorization.

51129281 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7304190.

The product of its digits is 1440, while the sum is 29.

The square root of 51129281 is about 7150.4741800806. The cubic root of 51129281 is about 371.1560651444.

It can be divided in two parts, 511 and 29281, that added together give a palindrome (29792).

The spelling of 51129281 in words is "fifty-one million, one hundred twenty-nine thousand, two hundred eighty-one".