51781281 has 8 divisors (see below), whose sum is σ = 69305280. Its totient is φ = 34389072.

The previous prime is 51781273. The next prime is 51781283. The reversal of 51781281 is 18218715.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 51781281 - 2³ = 51781273 is a prime.

It is a super-2 number, since 2×51781281² = 5362602124001922, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (51781283) 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, 32026 + ... + 33603.

It is an arithmetic number, because the mean of its divisors is an integer number (8663160).

Almost surely, 2^51781281 is an apocalyptic number.

It is an amenable number.

51781281 is a deficient number, since it is larger than the sum of its proper divisors (17523999).

51781281 is a wasteful number, since it uses less digits than its factorization.

51781281 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 65895.

The product of its digits is 4480, while the sum is 33.

The square root of 51781281 is about 7195.9211363105. The cubic root of 51781281 is about 372.7270654389.

Adding to 51781281 its reverse (18218715), we get a palindrome (69999996).

The spelling of 51781281 in words is "fifty-one million, seven hundred eighty-one thousand, two hundred eighty-one".