51240281 has 4 divisors (see below), whose sum is σ = 51255312. Its totient is φ = 51225252.

The previous prime is 51240253. The next prime is 51240307. The reversal of 51240281 is 18204215.

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 a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 18204215 = 5 ⋅3640843.

It is a cyclic number.

It is not a de Polignac number, because 51240281 - 2¹⁴ = 51223897 is a prime.

It is a super-2 number, since 2×51240281² = 5251132793917922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (51240221) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 326 + ... + 10128.

It is an arithmetic number, because the mean of its divisors is an integer number (12813828).

Almost surely, 2^51240281 is an apocalyptic number.

It is an amenable number.

51240281 is a deficient number, since it is larger than the sum of its proper divisors (15031).

51240281 is an equidigital number, since it uses as much as digits as its factorization.

51240281 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15030.

The product of its (nonzero) digits is 640, while the sum is 23.

The square root of 51240281 is about 7158.2316950487. The cubic root of 51240281 is about 371.4244602461.

Adding to 51240281 its reverse (18204215), we get a palindrome (69444496).

The spelling of 51240281 in words is "fifty-one million, two hundred forty thousand, two hundred eighty-one".