64651221 has 12 divisors (see below), whose sum is σ = 98878572. Its totient is φ = 40565376.

The previous prime is 64651207. The next prime is 64651241. The reversal of 64651221 is 12215646.

64651221 is a `hidden beast` number, since 6 + 4 + 651 + 2 + 2 + 1 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 21288996 + 43362225 = 4614^2 + 6585^2 .

It is not a de Polignac number, because 64651221 - 2¹⁷ = 64520149 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (64651201) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 211126 + ... + 211431.

It is an arithmetic number, because the mean of its divisors is an integer number (8239881).

Almost surely, 2^64651221 is an apocalyptic number.

It is an amenable number.

64651221 is a deficient number, since it is larger than the sum of its proper divisors (34227351).

64651221 is a wasteful number, since it uses less digits than its factorization.

64651221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 422580 (or 422577 counting only the distinct ones).

The product of its digits is 2880, while the sum is 27.

The square root of 64651221 is about 8040.5982986343. The cubic root of 64651221 is about 401.3521345966.

Adding to 64651221 its reverse (12215646), we get a palindrome (76866867).

The spelling of 64651221 in words is "sixty-four million, six hundred fifty-one thousand, two hundred twenty-one".