661021062172 has 12 divisors (see below), whose sum is σ = 1156899229416. Its totient is φ = 330478425200.

The previous prime is 661021062109. The next prime is 661021062173. The reversal of 661021062172 is 271260120166.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661021062173) 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 3 ways as a sum of consecutive naturals, for example, 7980118 + ... + 8062525.

It is an arithmetic number, because the mean of its divisors is an integer number (96408269118).

Almost surely, 2^661021062172 is an apocalyptic number.

It is an amenable number.

661021062172 is a deficient number, since it is larger than the sum of its proper divisors (495878167244).

661021062172 is a wasteful number, since it uses less digits than its factorization.

661021062172 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16052948 (or 16052946 counting only the distinct ones).

The product of its (nonzero) digits is 12096, while the sum is 34.

The spelling of 661021062172 in words is "six hundred sixty-one billion, twenty-one million, sixty-two thousand, one hundred seventy-two".