64815944025661 has 12 divisors (see below), whose sum is σ = 67211023943700. Its totient is φ = 62503554931328.

The previous prime is 64815944025653. The next prime is 64815944025667. The reversal of 64815944025661 is 16652044951846.

It can be written as a sum of positive squares in 6 ways, for example, as 12725586482436 + 52090357543225 = 3567294^2 + 7217365^2 .

It is not a de Polignac number, because 64815944025661 - 2³ = 64815944025653 is a prime.

It is a super-2 number, since 2×64815944025661² (a number of 28 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 64815944025661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (64815944025667) 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, 46952566 + ... + 48313303.

It is an arithmetic number, because the mean of its divisors is an integer number (5600918661975).

Almost surely, 2^{64815944025661} is an apocalyptic number.

It is an amenable number.

64815944025661 is a deficient number, since it is larger than the sum of its proper divisors (2395079918039).

64815944025661 is an equidigital number, since it uses as much as digits as its factorization.

64815944025661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 95266736 (or 95266707 counting only the distinct ones).

The product of its (nonzero) digits is 49766400, while the sum is 61.

The spelling of 64815944025661 in words is "sixty-four trillion, eight hundred fifteen billion, nine hundred forty-four million, twenty-five thousand, six hundred sixty-one".