51720505 has 8 divisors (see below), whose sum is σ = 62105472. Its totient is φ = 41349168.

The previous prime is 51720499. The next prime is 51720509. The reversal of 51720505 is 50502715.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 51720505 - 2¹⁵ = 51687737 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 51720505.

It is not an unprimeable number, because it can be changed into a prime (51720509) 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, 9174 + ... + 13696.

It is an arithmetic number, because the mean of its divisors is an integer number (7763184).

Almost surely, 2^51720505 is an apocalyptic number.

It is an amenable number.

51720505 is a deficient number, since it is larger than the sum of its proper divisors (10384967).

51720505 is a wasteful number, since it uses less digits than its factorization.

51720505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6815.

The product of its (nonzero) digits is 1750, while the sum is 25.

The square root of 51720505 is about 7191.6969485651. The cubic root of 51720505 is about 372.5811843530.

It can be divided in two parts, 51720 and 505, that added together give a palindrome (52225).

The spelling of 51720505 in words is "fifty-one million, seven hundred twenty thousand, five hundred five".