51688906 has 4 divisors (see below), whose sum is σ = 77533362. Its totient is φ = 25844452.

The previous prime is 51688883. The next prime is 51688909. The reversal of 51688906 is 60988615.

51688906 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 60988615 = 5 ⋅12197723.

It can be written as a sum of positive squares in only one way, i.e., 48233025 + 3455881 = 6945^2 + 1859^2 .

It is not an unprimeable number, because it can be changed into a prime (51688909) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 12922225 + ... + 12922228.

Almost surely, 2^51688906 is an apocalyptic number.

51688906 is a deficient number, since it is larger than the sum of its proper divisors (25844456).

51688906 is a wasteful number, since it uses less digits than its factorization.

51688906 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25844455.

The product of its (nonzero) digits is 103680, while the sum is 43.

The square root of 51688906 is about 7189.4997044301. The cubic root of 51688906 is about 372.5052918786.

The spelling of 51688906 in words is "fifty-one million, six hundred eighty-eight thousand, nine hundred six".