51690209 has 8 divisors (see below), whose sum is σ = 53817960. Its totient is φ = 49585536.

The previous prime is 51690179. The next prime is 51690263. The reversal of 51690209 is 90209615.

51690209 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 1677025 + 50013184 = 1295^2 + 7072^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-51690209 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (51695209) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1124 + ... + 10229.

It is an arithmetic number, because the mean of its divisors is an integer number (6727245).

Almost surely, 2^51690209 is an apocalyptic number.

It is an amenable number.

51690209 is a deficient number, since it is larger than the sum of its proper divisors (2127751).

51690209 is a wasteful number, since it uses less digits than its factorization.

51690209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11539.

The product of its (nonzero) digits is 4860, while the sum is 32.

The square root of 51690209 is about 7189.5903221255. The cubic root of 51690209 is about 372.5084219527.

The spelling of 51690209 in words is "fifty-one million, six hundred ninety thousand, two hundred nine".