64415921558209 has 81 divisors (see below), whose sum is σ = 73655064259569. Its totient is φ = 56307517943040.

The previous prime is 64415921558147. The next prime is 64415921558231. The reversal of 64415921558209 is 90285512951446.

It is a happy number.

The square root of 64415921558209 is 8025953.

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

It can be written as a sum of positive squares in 40 ways, for example, as 35974264601025 + 28441656957184 = 5997855^2 + 5333072^2 .

It is not a de Polignac number, because 64415921558209 - 2²⁷ = 64415787340481 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (61).

It is not an unprimeable number, because it can be changed into a prime (64415921558279) 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 80 ways as a sum of consecutive naturals, for example, 184572840967 + ... + 184572841315.

Almost surely, 2^{64415921558209} is an apocalyptic number.

64415921558209 is the 8025953-rd square number.

64415921558209 is the 4012977-th centered octagonal number.

It is an amenable number.

64415921558209 is a deficient number, since it is larger than the sum of its proper divisors (9239142701360).

64415921558209 is an frugal number, since it uses more digits than its factorization.

64415921558209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 904 (or 452 counting only the distinct ones).

The product of its (nonzero) digits is 31104000, while the sum is 61.

The spelling of 64415921558209 in words is "sixty-four trillion, four hundred fifteen billion, nine hundred twenty-one million, five hundred fifty-eight thousand, two hundred nine".