64721549 has 8 divisors (see below), whose sum is σ = 66173592.
Its totient is φ = 63282240.
The previous prime is 64721537. The next prime is 64721557. The reversal of 64721549 is 94512746.
It can be written as a sum of positive squares in 4 ways, for example, as 22705225 + 42016324 = 4765^2 + 6482^2
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 64721549 - 224 = 47944333 is a prime.
It is a super-3 number, since 3×647215493 (a number of 24 digits) contains 333 as substring.
It is a Duffinian number.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (64721509) 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, 7487 + ... + 13619.
It is an arithmetic number, because the mean of its divisors is an integer number (8271699).
Almost surely, 264721549 is an apocalyptic number.
It is an amenable number.
64721549 is a deficient number, since it is larger than the sum of its proper divisors (1452043).
64721549 is a wasteful number, since it uses less digits than its factorization.
64721549 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 6367.
The product of its digits is 60480, while the sum is 38.
The square root of 64721549 is about 8044.9704163533.
The cubic root of 64721549 is about 401.4976129740.
The spelling of 64721549 in words is "sixty-four million, seven hundred twenty-one thousand, five hundred forty-nine".