661659972843 has 32 divisors (see below), whose sum is σ = 947826696960. Its totient is φ = 409286666880.

The previous prime is 661659972823. The next prime is 661659972851. The reversal of 661659972843 is 348279956166.

It is not a de Polignac number, because 661659972843 - 2³² = 657365005547 is a prime.

It is not an unprimeable number, because it can be changed into a prime (661659972803) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1533205 + ... + 1916777.

It is an arithmetic number, because the mean of its divisors is an integer number (29619584280).

Almost surely, 2^661659972843 is an apocalyptic number.

661659972843 is a deficient number, since it is larger than the sum of its proper divisors (286166724117).

661659972843 is a wasteful number, since it uses less digits than its factorization.

661659972843 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 384219.

The product of its digits is 117573120, while the sum is 66.

The spelling of 661659972843 in words is "six hundred sixty-one billion, six hundred fifty-nine million, nine hundred seventy-two thousand, eight hundred forty-three".