51697409 has 2 divisors, whose sum is σ = 51697410. Its totient is φ = 51697408.

The previous prime is 51697381. The next prime is 51697453. The reversal of 51697409 is 90479615.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 42211009 + 9486400 = 6497^2 + 3080^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-51697409 is a prime.

It is not a weakly prime, because it can be changed into another prime (51697489) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25848704 + 25848705.

It is an arithmetic number, because the mean of its divisors is an integer number (25848705).

Almost surely, 2^51697409 is an apocalyptic number.

It is an amenable number.

51697409 is a deficient number, since it is larger than the sum of its proper divisors (1).

51697409 is an equidigital number, since it uses as much as digits as its factorization.

51697409 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 68040, while the sum is 41.

The square root of 51697409 is about 7190.0910286310. The cubic root of 51697409 is about 372.5257168858.

The spelling of 51697409 in words is "fifty-one million, six hundred ninety-seven thousand, four hundred nine".