661399616 has 14 divisors (see below), whose sum is σ = 1312464990. Its totient is φ = 330699776.

The previous prime is 661399597. The next prime is 661399621. The reversal of 661399616 is 616993166.

It can be written as a sum of positive squares in only one way, i.e., 585640000 + 75759616 = 24200^2 + 8704^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5167121 + ... + 5167248.

Almost surely, 2^661399616 is an apocalyptic number.

It is an amenable number.

661399616 is a deficient number, since it is larger than the sum of its proper divisors (651065374).

661399616 is a wasteful number, since it uses less digits than its factorization.

661399616 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10334381 (or 10334371 counting only the distinct ones).

The product of its digits is 314928, while the sum is 47.

The square root of 661399616 is about 25717.6907205915. The cubic root of 661399616 is about 871.2737830394.

The spelling of 661399616 in words is "six hundred sixty-one million, three hundred ninety-nine thousand, six hundred sixteen".