51278781 has 8 divisors (see below), whose sum is σ = 70219744. Its totient is φ = 33261840.

The previous prime is 51278761. The next prime is 51278789. The reversal of 51278781 is 18787215.

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

It is not a de Polignac number, because 51278781 - 2¹⁷ = 51147709 is a prime.

It is a super-2 number, since 2×51278781² = 5259026761691922, 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 (51278789) 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, 230875 + ... + 231096.

It is an arithmetic number, because the mean of its divisors is an integer number (8777468).

Almost surely, 2^51278781 is an apocalyptic number.

It is an amenable number.

51278781 is a deficient number, since it is larger than the sum of its proper divisors (18940963).

51278781 is a wasteful number, since it uses less digits than its factorization.

51278781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 462011.

The product of its digits is 31360, while the sum is 39.

The square root of 51278781 is about 7160.9204017361. The cubic root of 51278781 is about 371.5174616992.

The spelling of 51278781 in words is "fifty-one million, two hundred seventy-eight thousand, seven hundred eighty-one".