51440309 has 4 divisors (see below), whose sum is σ = 52018380. Its totient is φ = 50862240.

The previous prime is 51440303. The next prime is 51440327. The reversal of 51440309 is 90304415.

51440309 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 25786084 + 25654225 = 5078^2 + 5065^2 .

It is a cyclic number.

It is not a de Polignac number, because 51440309 - 2⁴ = 51440293 is a prime.

It is a super-2 number, since 2×51440309² = 5292210780030962, which contains 22 as substring.

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 (51440303) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 288902 + ... + 289079.

It is an arithmetic number, because the mean of its divisors is an integer number (13004595).

Almost surely, 2^51440309 is an apocalyptic number.

It is an amenable number.

51440309 is a deficient number, since it is larger than the sum of its proper divisors (578071).

51440309 is an equidigital number, since it uses as much as digits as its factorization.

51440309 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 578070.

The product of its (nonzero) digits is 2160, while the sum is 26.

The square root of 51440309 is about 7172.1899723864. The cubic root of 51440309 is about 371.9071457653.

The spelling of 51440309 in words is "fifty-one million, four hundred forty thousand, three hundred nine".