51691229 has 18 divisors (see below), whose sum is σ = 56749950. Its totient is φ = 47072880.

The previous prime is 51691223. The next prime is 51691231. The reversal of 51691229 is 92219615.

It can be written as a sum of positive squares in only one way, i.e., 34692100 + 16999129 = 5890^2 + 4123^2 .

It is not a de Polignac number, because 51691229 - 2²⁰ = 50642653 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51691223) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 346847 + ... + 346995.

It is an arithmetic number, because the mean of its divisors is an integer number (3152775).

Almost surely, 2^51691229 is an apocalyptic number.

It is an amenable number.

51691229 is a deficient number, since it is larger than the sum of its proper divisors (5058721).

51691229 is a wasteful number, since it uses less digits than its factorization.

51691229 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 249 (or 199 counting only the distinct ones).

The product of its digits is 9720, while the sum is 35.

The square root of 51691229 is about 7189.6612576672. The cubic root of 51691229 is about 372.5108721659.

The spelling of 51691229 in words is "fifty-one million, six hundred ninety-one thousand, two hundred twenty-nine".