661206820001 has 16 divisors (see below), whose sum is σ = 813847488384. Its totient is φ = 523117626624.

The previous prime is 661206819979. The next prime is 661206820033. The reversal of 661206820001 is 100028602166.

It is a cyclic number.

It is not a de Polignac number, because 661206820001 - 2³⁰ = 660133078177 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 661206820001.

It is not an unprimeable number, because it can be changed into a prime (661206820081) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1168361 + ... + 1639353.

It is an arithmetic number, because the mean of its divisors is an integer number (50865468024).

Almost surely, 2^661206820001 is an apocalyptic number.

It is an amenable number.

661206820001 is a deficient number, since it is larger than the sum of its proper divisors (152640668383).

661206820001 is a wasteful number, since it uses less digits than its factorization.

661206820001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 486440.

The product of its (nonzero) digits is 6912, while the sum is 32.

The spelling of 661206820001 in words is "six hundred sixty-one billion, two hundred six million, eight hundred twenty thousand, one".