51989809 has 2 divisors, whose sum is σ = 51989810. Its totient is φ = 51989808.

The previous prime is 51989803. The next prime is 51989843. The reversal of 51989809 is 90898915.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 27457600 + 24532209 = 5240^2 + 4953^2 .

It is a cyclic number.

It is not a de Polignac number, because 51989809 - 2³ = 51989801 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (51989801) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25994904 + 25994905.

It is an arithmetic number, because the mean of its divisors is an integer number (25994905).

Almost surely, 2^51989809 is an apocalyptic number.

It is an amenable number.

51989809 is a deficient number, since it is larger than the sum of its proper divisors (1).

51989809 is an equidigital number, since it uses as much as digits as its factorization.

51989809 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 233280, while the sum is 49.

The square root of 51989809 is about 7210.3958975912. The cubic root of 51989809 is about 373.2267307417.

The spelling of 51989809 in words is "fifty-one million, nine hundred eighty-nine thousand, eight hundred nine".