51806551 has 4 divisors (see below), whose sum is σ = 52179400. Its totient is φ = 51433704.

The previous prime is 51806537. The next prime is 51806569. The reversal of 51806551 is 15560815.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 51806551 - 2⁵ = 51806519 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51806581) 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, 186216 + ... + 186493.

It is an arithmetic number, because the mean of its divisors is an integer number (13044850).

Almost surely, 2^51806551 is an apocalyptic number.

51806551 is a deficient number, since it is larger than the sum of its proper divisors (372849).

51806551 is a wasteful number, since it uses less digits than its factorization.

51806551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 372848.

The product of its (nonzero) digits is 6000, while the sum is 31.

The square root of 51806551 is about 7197.6767779611. The cubic root of 51806551 is about 372.7876876110.

The spelling of 51806551 in words is "fifty-one million, eight hundred six thousand, five hundred fifty-one".