51617209 has 4 divisors (see below), whose sum is σ = 58991104. Its totient is φ = 44243316.

The previous prime is 51617197. The next prime is 51617227. The reversal of 51617209 is 90271615.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 51617209 - 2¹⁵ = 51584441 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (51617239) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3686937 + ... + 3686950.

It is an arithmetic number, because the mean of its divisors is an integer number (14747776).

Almost surely, 2^51617209 is an apocalyptic number.

It is an amenable number.

51617209 is a deficient number, since it is larger than the sum of its proper divisors (7373895).

51617209 is an equidigital number, since it uses as much as digits as its factorization.

51617209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7373894.

The product of its (nonzero) digits is 3780, while the sum is 31.

The square root of 51617209 is about 7184.5117440227. The cubic root of 51617209 is about 372.3329797905.

The spelling of 51617209 in words is "fifty-one million, six hundred seventeen thousand, two hundred nine".