51231709 has 4 divisors (see below), whose sum is σ = 51291004. Its totient is φ = 51172416.

The previous prime is 51231703. The next prime is 51231721. The reversal of 51231709 is 90713215.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 90713215 = 5 ⋅18142643.

It can be written as a sum of positive squares in 2 ways, for example, as 45091225 + 6140484 = 6715^2 + 2478^2 .

It is a cyclic number.

It is not a de Polignac number, because 51231709 - 2¹³ = 51223517 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51231703) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 28332 + ... + 30085.

It is an arithmetic number, because the mean of its divisors is an integer number (12822751).

Almost surely, 2^51231709 is an apocalyptic number.

It is an amenable number.

51231709 is a deficient number, since it is larger than the sum of its proper divisors (59295).

51231709 is an equidigital number, since it uses as much as digits as its factorization.

51231709 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 59294.

The product of its (nonzero) digits is 1890, while the sum is 28.

The square root of 51231709 is about 7157.6329187798. The cubic root of 51231709 is about 371.4037471927.

The spelling of 51231709 in words is "fifty-one million, two hundred thirty-one thousand, seven hundred nine".