661039816 has 8 divisors (see below), whose sum is σ = 1239449670. Its totient is φ = 330519904.

The previous prime is 661039787. The next prime is 661039829. The reversal of 661039816 is 618930166.

661039816 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 658948900 + 2090916 = 25670^2 + 1446^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 41314981 + ... + 41314996.

Almost surely, 2^661039816 is an apocalyptic number.

It is an amenable number.

661039816 is a deficient number, since it is larger than the sum of its proper divisors (578409854).

661039816 is a wasteful number, since it uses less digits than its factorization.

661039816 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 82629983 (or 82629979 counting only the distinct ones).

The product of its (nonzero) digits is 46656, while the sum is 40.

The square root of 661039816 is about 25710.6945841609. The cubic root of 661039816 is about 871.1157640135.

The spelling of 661039816 in words is "six hundred sixty-one million, thirty-nine thousand, eight hundred sixteen".