51721717 has 8 divisors (see below), whose sum is σ = 52776632. Its totient is φ = 50673600.

The previous prime is 51721697. The next prime is 51721721. The reversal of 51721717 is 71712715.

It can be written as a sum of positive squares in 4 ways, for example, as 1962801 + 49758916 = 1401^2 + 7054^2 .

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-51721717 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 (51721757) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15367 + ... + 18427.

It is an arithmetic number, because the mean of its divisors is an integer number (6597079).

Almost surely, 2^51721717 is an apocalyptic number.

It is an amenable number.

51721717 is a deficient number, since it is larger than the sum of its proper divisors (1054915).

51721717 is a wasteful number, since it uses less digits than its factorization.

51721717 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3399.

The product of its digits is 3430, while the sum is 31.

The square root of 51721717 is about 7191.7812119113. The cubic root of 51721717 is about 372.5840946421.

It can be divided in two parts, 5172 and 1717, that added together give a square (6889 = 83²).

The spelling of 51721717 in words is "fifty-one million, seven hundred twenty-one thousand, seven hundred seventeen".