64485015721 has 9 divisors (see below), whose sum is σ = 75015249399. Its totient is φ = 55271346984.

The previous prime is 64485015671. The next prime is 64485015739. The reversal of 64485015721 is 12751058446.

The square root of 64485015721 is 253939.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 53086464025 + 11398551696 = 230405^2 + 106764^2 .

It is not a de Polignac number, because 64485015721 - 2¹¹ = 64485013673 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (64485015821) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 1759435 + ... + 1795711.

It is an arithmetic number, because the mean of its divisors is an integer number (8335027711).

Almost surely, 2^64485015721 is an apocalyptic number.

64485015721 is the 253939-th square number.

64485015721 is the 126970-th centered octagonal number.

It is an amenable number.

64485015721 is a deficient number, since it is larger than the sum of its proper divisors (10530233678).

64485015721 is an frugal number, since it uses more digits than its factorization.

64485015721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 72568 (or 36284 counting only the distinct ones).

The product of its (nonzero) digits is 268800, while the sum is 43.

The spelling of 64485015721 in words is "sixty-four billion, four hundred eighty-five million, fifteen thousand, seven hundred twenty-one".