661500111001 has 4 divisors (see below), whose sum is σ = 664074041652. Its totient is φ = 658926180352.

The previous prime is 661500110989. The next prime is 661500111031. The reversal of 661500111001 is 100111005166.

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 650829427600 + 10670683401 = 806740^2 + 103299^2 .

It is a cyclic number.

It is not a de Polignac number, because 661500111001 - 2²¹ = 661498013849 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (661500111031) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1286964940 + ... + 1286965453.

It is an arithmetic number, because the mean of its divisors is an integer number (166018510413).

Almost surely, 2^661500111001 is an apocalyptic number.

It is an amenable number.

661500111001 is a deficient number, since it is larger than the sum of its proper divisors (2573930651).

661500111001 is a wasteful number, since it uses less digits than its factorization.

661500111001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2573930650.

The product of its (nonzero) digits is 180, while the sum is 22.

Adding to 661500111001 its reverse (100111005166), we get a palindrome (761611116167).

The spelling of 661500111001 in words is "six hundred sixty-one billion, five hundred million, one hundred eleven thousand, one".