51810809 has 2 divisors, whose sum is σ = 51810810. Its totient is φ = 51810808.

The previous prime is 51810799. The next prime is 51810817. The reversal of 51810809 is 90801815.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 49392784 + 2418025 = 7028^2 + 1555^2 .

It is a cyclic number.

It is not a de Polignac number, because 51810809 - 2⁸ = 51810553 is a prime.

It is not a weakly prime, because it can be changed into another prime (51810859) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25905404 + 25905405.

It is an arithmetic number, because the mean of its divisors is an integer number (25905405).

Almost surely, 2^51810809 is an apocalyptic number.

It is an amenable number.

51810809 is a deficient number, since it is larger than the sum of its proper divisors (1).

51810809 is an equidigital number, since it uses as much as digits as its factorization.

51810809 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2880, while the sum is 32.

The square root of 51810809 is about 7197.9725617704. The cubic root of 51810809 is about 372.7979005182.

The spelling of 51810809 in words is "fifty-one million, eight hundred ten thousand, eight hundred nine".