51721806 has 16 divisors (see below), whose sum is σ = 103890384. Its totient is φ = 17166144.

The previous prime is 51721801. The next prime is 51721807. The reversal of 51721806 is 60812715.

51721806 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51721801) 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 in 7 ways as a sum of consecutive naturals, for example, 17101 + ... + 19896.

It is an arithmetic number, because the mean of its divisors is an integer number (6493149).

Almost surely, 2^51721806 is an apocalyptic number.

51721806 is an abundant number, since it is smaller than the sum of its proper divisors (52168578).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

51721806 is a wasteful number, since it uses less digits than its factorization.

51721806 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37235.

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

The square root of 51721806 is about 7191.7873995273. The cubic root of 51721806 is about 372.5843083497.

Subtracting 51721806 from its reverse (60812715), we obtain a palindrome (9090909).

The spelling of 51721806 in words is "fifty-one million, seven hundred twenty-one thousand, eight hundred six".