51666749 has 4 divisors (see below), whose sum is σ = 51687420. Its totient is φ = 51646080.

The previous prime is 51666737. The next prime is 51666767. The reversal of 51666749 is 94766615.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 94766615 = 5 ⋅18953323.

It can be written as a sum of positive squares in 2 ways, for example, as 32569849 + 19096900 = 5707^2 + 4370^2 .

It is a cyclic number.

It is not a de Polignac number, because 51666749 - 2⁴ = 51666733 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51666709) 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, 5972 + ... + 11789.

It is an arithmetic number, because the mean of its divisors is an integer number (12921855).

Almost surely, 2^51666749 is an apocalyptic number.

It is an amenable number.

51666749 is a deficient number, since it is larger than the sum of its proper divisors (20671).

51666749 is a wasteful number, since it uses less digits than its factorization.

51666749 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20670.

The product of its digits is 272160, while the sum is 44.

The square root of 51666749 is about 7187.9586114557. The cubic root of 51666749 is about 372.4520581514.

The spelling of 51666749 in words is "fifty-one million, six hundred sixty-six thousand, seven hundred forty-nine".