51720705 has 12 divisors (see below), whose sum is σ = 89649300. Its totient is φ = 27584352.

The previous prime is 51720689. The next prime is 51720707. The reversal of 51720705 is 50702715.

It can be written as a sum of positive squares in 2 ways, for example, as 17040384 + 34680321 = 4128^2 + 5889^2 .

It is not a de Polignac number, because 51720705 - 2⁴ = 51720689 is a prime.

It is not an unprimeable number, because it can be changed into a prime (51720707) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 574630 + ... + 574719.

It is an arithmetic number, because the mean of its divisors is an integer number (7470775).

Almost surely, 2^51720705 is an apocalyptic number.

It is an amenable number.

51720705 is a deficient number, since it is larger than the sum of its proper divisors (37928595).

51720705 is a wasteful number, since it uses less digits than its factorization.

51720705 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1149360 (or 1149357 counting only the distinct ones).

The product of its (nonzero) digits is 2450, while the sum is 27.

The square root of 51720705 is about 7191.7108534757. The cubic root of 51720705 is about 372.5816646018.

It can be divided in two parts, 51720 and 705, that added together give a palindrome (52425).

The spelling of 51720705 in words is "fifty-one million, seven hundred twenty thousand, seven hundred five".