51551509 has 2 divisors, whose sum is σ = 51551510. Its totient is φ = 51551508.

The previous prime is 51551501. The next prime is 51551537. The reversal of 51551509 is 90515515.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 43850884 + 7700625 = 6622^2 + 2775^2 .

It is a cyclic number.

It is not a de Polignac number, because 51551509 - 2³ = 51551501 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (51551501) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25775754 + 25775755.

It is an arithmetic number, because the mean of its divisors is an integer number (25775755).

Almost surely, 2^51551509 is an apocalyptic number.

It is an amenable number.

51551509 is a deficient number, since it is larger than the sum of its proper divisors (1).

51551509 is an equidigital number, since it uses as much as digits as its factorization.

51551509 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5625, while the sum is 31.

The square root of 51551509 is about 7179.9379523781. The cubic root of 51551509 is about 372.1749403602.

The spelling of 51551509 in words is "fifty-one million, five hundred fifty-one thousand, five hundred nine".