64721601 has 72 divisors (see below), whose sum is σ = 117641160. Its totient is φ = 34062336.

The previous prime is 64721599. The next prime is 64721611. The reversal of 64721601 is 10612746.

64721601 is a `hidden beast` number, since 647 + 2 + 16 + 0 + 1 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 7568001 + 57153600 = 2751^2 + 7560^2 .

It is not a de Polignac number, because 64721601 - 2¹ = 64721599 is a prime.

It is a super-3 number, since 3×64721601³ (a number of 24 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (64721611) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 667185 + ... + 667281.

It is an arithmetic number, because the mean of its divisors is an integer number (1633905).

Almost surely, 2^64721601 is an apocalyptic number.

It is an amenable number.

64721601 is a deficient number, since it is larger than the sum of its proper divisors (52919559).

64721601 is a wasteful number, since it uses less digits than its factorization.

64721601 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 223 (or 213 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 27.

The square root of 64721601 is about 8044.9736481856. The cubic root of 64721601 is about 401.4977205007.

The spelling of 64721601 in words is "sixty-four million, seven hundred twenty-one thousand, six hundred one".