661243312145 has 16 divisors (see below), whose sum is σ = 862369551120. Its totient is φ = 483822906624.

The previous prime is 661243312133. The next prime is 661243312181. The reversal of 661243312145 is 541213342166.

It can be written as a sum of positive squares in 8 ways, for example, as 23661822976 + 637581489169 = 153824^2 + 798487^2 .

It is a cyclic number.

It is not a de Polignac number, because 661243312145 - 2⁸ = 661243311889 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 661243312099 and 661243312108.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 46657934 + ... + 46672103.

It is an arithmetic number, because the mean of its divisors is an integer number (53898096945).

Almost surely, 2^661243312145 is an apocalyptic number.

661243312145 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

It is an amenable number.

661243312145 is a deficient number, since it is larger than the sum of its proper divisors (201126238975).

661243312145 is a wasteful number, since it uses less digits than its factorization.

661243312145 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 93330164.

The product of its digits is 103680, while the sum is 38.

The spelling of 661243312145 in words is "six hundred sixty-one billion, two hundred forty-three million, three hundred twelve thousand, one hundred forty-five".