51666649 has 2 divisors, whose sum is σ = 51666650. Its totient is φ = 51666648.

The previous prime is 51666617. The next prime is 51666707. The reversal of 51666649 is 94666615.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 46826649 + 4840000 = 6843^2 + 2200^2 .

It is a cyclic number.

It is not a de Polignac number, because 51666649 - 2⁵ = 51666617 is a prime.

It is not a weakly prime, because it can be changed into another prime (51660649) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25833324 + 25833325.

It is an arithmetic number, because the mean of its divisors is an integer number (25833325).

Almost surely, 2^51666649 is an apocalyptic number.

It is an amenable number.

51666649 is a deficient number, since it is larger than the sum of its proper divisors (1).

51666649 is an equidigital number, since it uses as much as digits as its factorization.

51666649 is an evil number, because the sum of its binary digits is even.

The product of its digits is 233280, while the sum is 43.

The square root of 51666649 is about 7187.9516553744. The cubic root of 51666649 is about 372.4518178600.

The spelling of 51666649 in words is "fifty-one million, six hundred sixty-six thousand, six hundred forty-nine".