51206781 has 8 divisors (see below), whose sum is σ = 68813824. Its totient is φ = 33868800.

The previous prime is 51206777. The next prime is 51206791. The reversal of 51206781 is 18760215.

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

It is not a de Polignac number, because 51206781 - 2² = 51206777 is a prime.

It is a super-2 number, since 2×51206781² = 5244268840763922, 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 (51206711) 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, 66820 + ... + 67581.

It is an arithmetic number, because the mean of its divisors is an integer number (8601728).

Almost surely, 2^51206781 is an apocalyptic number.

It is an amenable number.

51206781 is a deficient number, since it is larger than the sum of its proper divisors (17607043).

51206781 is a wasteful number, since it uses less digits than its factorization.

51206781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 134531.

The product of its (nonzero) digits is 3360, while the sum is 30.

The square root of 51206781 is about 7155.8913490913. The cubic root of 51206781 is about 371.3434989934.

Adding to 51206781 its reverse (18760215), we get a palindrome (69966996).

The spelling of 51206781 in words is "fifty-one million, two hundred six thousand, seven hundred eighty-one".