64947181221 has 12 divisors (see below), whose sum is σ = 101028948748. Its totient is φ = 39967496064.

The previous prime is 64947181213. The next prime is 64947181237. The reversal of 64947181221 is 12218174946.

It can be written as a sum of positive squares in 2 ways, for example, as 12970020996 + 51977160225 = 113886^2 + 227985^2 .

It is not a de Polignac number, because 64947181221 - 2³ = 64947181213 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (64947181241) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 277551940 + ... + 277552173.

Almost surely, 2^64947181221 is an apocalyptic number.

It is an amenable number.

64947181221 is a deficient number, since it is larger than the sum of its proper divisors (36081767527).

64947181221 is a wasteful number, since it uses less digits than its factorization.

64947181221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 555104132 (or 555104129 counting only the distinct ones).

The product of its digits is 193536, while the sum is 45.

The spelling of 64947181221 in words is "sixty-four billion, nine hundred forty-seven million, one hundred eighty-one thousand, two hundred twenty-one".