661661012 has 24 divisors (see below), whose sum is σ = 1226897280. Its totient is φ = 311146880.

The previous prime is 661661009. The next prime is 661661017. The reversal of 661661012 is 210166166.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661661017) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 128789 + ... + 133827.

It is an arithmetic number, because the mean of its divisors is an integer number (51120720).

Almost surely, 2^661661012 is an apocalyptic number.

It is an amenable number.

661661012 is a deficient number, since it is larger than the sum of its proper divisors (565236268).

661661012 is a wasteful number, since it uses less digits than its factorization.

661661012 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6991 (or 6989 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 29.

The square root of 661661012 is about 25722.7722456193. The cubic root of 661661012 is about 871.3885484952.

The spelling of 661661012 in words is "six hundred sixty-one million, six hundred sixty-one thousand, twelve".