51212509 has 2 divisors, whose sum is σ = 51212510. Its totient is φ = 51212508.

The previous prime is 51212507. The next prime is 51212519. The reversal of 51212509 is 90521215.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 39413284 + 11799225 = 6278^2 + 3435^2 .

It is a cyclic number.

It is not a de Polignac number, because 51212509 - 2¹ = 51212507 is a prime.

Together with 51212507, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (51212503) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25606254 + 25606255.

It is an arithmetic number, because the mean of its divisors is an integer number (25606255).

Almost surely, 2^51212509 is an apocalyptic number.

It is an amenable number.

51212509 is a deficient number, since it is larger than the sum of its proper divisors (1).

51212509 is an equidigital number, since it uses as much as digits as its factorization.

51212509 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 900, while the sum is 25.

The square root of 51212509 is about 7156.2915675649. The cubic root of 51212509 is about 371.3573446614.

The spelling of 51212509 in words is "fifty-one million, two hundred twelve thousand, five hundred nine".