61217115665 has 4 divisors (see below), whose sum is σ = 73460538804. Its totient is φ = 48973692528.

The previous prime is 61217115647. The next prime is 61217115727. The reversal of 61217115665 is 56651171216.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 15516937489 + 45700178176 = 124567^2 + 213776^2 .

It is a cyclic number.

It is not a de Polignac number, because 61217115665 - 2¹⁰ = 61217114641 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6121711562 + ... + 6121711571.

It is an arithmetic number, because the mean of its divisors is an integer number (18365134701).

Almost surely, 2^61217115665 is an apocalyptic number.

It is an amenable number.

61217115665 is a deficient number, since it is larger than the sum of its proper divisors (12243423139).

61217115665 is a wasteful number, since it uses less digits than its factorization.

61217115665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12243423138.

The product of its digits is 75600, while the sum is 41.

The spelling of 61217115665 in words is "sixty-one billion, two hundred seventeen million, one hundred fifteen thousand, six hundred sixty-five".