51216509 has 2 divisors, whose sum is σ = 51216510. Its totient is φ = 51216508.

The previous prime is 51216493. The next prime is 51216521. The reversal of 51216509 is 90561215.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 51079609 + 136900 = 7147^2 + 370^2 .

It is a cyclic number.

It is not a de Polignac number, because 51216509 - 2⁴ = 51216493 is a prime.

It is a super-3 number, since 3×51216509³ (a number of 24 digits) contains 333 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (51216589) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25608254 + 25608255.

It is an arithmetic number, because the mean of its divisors is an integer number (25608255).

Almost surely, 2^51216509 is an apocalyptic number.

It is an amenable number.

51216509 is a deficient number, since it is larger than the sum of its proper divisors (1).

51216509 is an equidigital number, since it uses as much as digits as its factorization.

51216509 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2700, while the sum is 29.

The square root of 51216509 is about 7156.5710364671. The cubic root of 51216509 is about 371.3670128117.

The spelling of 51216509 in words is "fifty-one million, two hundred sixteen thousand, five hundred nine".