65151721 has 4 divisors (see below), whose sum is σ = 66219844. Its totient is φ = 64083600.

The previous prime is 65151683. The next prime is 65151761. The reversal of 65151721 is 12715156.

65151721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 24651225 + 40500496 = 4965^2 + 6364^2 .

It is a cyclic number.

It is not a de Polignac number, because 65151721 - 2¹⁷ = 65020649 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 65151721.

It is not an unprimeable number, because it can be changed into a prime (65151761) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 533970 + ... + 534091.

It is an arithmetic number, because the mean of its divisors is an integer number (16554961).

Almost surely, 2^65151721 is an apocalyptic number.

65151721 is a gapful number since it is divisible by the number (61) formed by its first and last digit.

It is an amenable number.

65151721 is a deficient number, since it is larger than the sum of its proper divisors (1068123).

65151721 is a wasteful number, since it uses less digits than its factorization.

65151721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1068122.

The product of its digits is 2100, while the sum is 28.

The square root of 65151721 is about 8071.6616009345. The cubic root of 65151721 is about 402.3851679157.

Adding to 65151721 its reverse (12715156), we get a palindrome (77866877).

The spelling of 65151721 in words is "sixty-five million, one hundred fifty-one thousand, seven hundred twenty-one".