65415721 has 4 divisors (see below), whose sum is σ = 74760832. Its totient is φ = 56070612.

The previous prime is 65415709. The next prime is 65415739. The reversal of 65415721 is 12751456.

65415721 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, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 65415721 - 2⁹ = 65415209 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (65415761) 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, 4672545 + ... + 4672558.

It is an arithmetic number, because the mean of its divisors is an integer number (18690208).

Almost surely, 2^65415721 is an apocalyptic number.

It is an amenable number.

65415721 is a deficient number, since it is larger than the sum of its proper divisors (9345111).

65415721 is an equidigital number, since it uses as much as digits as its factorization.

65415721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9345110.

The product of its digits is 8400, while the sum is 31.

The square root of 65415721 is about 8087.9985781403. The cubic root of 65415721 is about 402.9279344566.

The spelling of 65415721 in words is "sixty-five million, four hundred fifteen thousand, seven hundred twenty-one".