51815866 has 16 divisors (see below), whose sum is σ = 81003240. Its totient is φ = 24828160.

The previous prime is 51815843. The next prime is 51815887. The reversal of 51815866 is 66851815.

It can be written as a sum of positive squares in 4 ways, for example, as 51480625 + 335241 = 7175^2 + 579^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4686 + ... + 11206.

Almost surely, 2^51815866 is an apocalyptic number.

51815866 is a deficient number, since it is larger than the sum of its proper divisors (29187374).

51815866 is a wasteful number, since it uses less digits than its factorization.

51815866 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6689.

The product of its digits is 57600, while the sum is 40.

The square root of 51815866 is about 7198.3238326710. The cubic root of 51815866 is about 372.8100291177.

It can be divided in two parts, 518 and 15866, that added together give a 14-th power (16384 = 2¹⁴).

The spelling of 51815866 in words is "fifty-one million, eight hundred fifteen thousand, eight hundred sixty-six".