661405544 has 16 divisors (see below), whose sum is σ = 1240478820. Its totient is φ = 330611200.

The previous prime is 661405531. The next prime is 661405559. The reversal of 661405544 is 445504166.

It can be written as a sum of positive squares in 2 ways, for example, as 588644644 + 72760900 = 24262^2 + 8530^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 26744 + ... + 45144.

Almost surely, 2^661405544 is an apocalyptic number.

It is an amenable number.

661405544 is a deficient number, since it is larger than the sum of its proper divisors (579073276).

661405544 is a wasteful number, since it uses less digits than its factorization.

661405544 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22900 (or 22896 counting only the distinct ones).

The product of its (nonzero) digits is 57600, while the sum is 35.

The square root of 661405544 is about 25717.8059717387. The cubic root of 661405544 is about 871.2763860525.

The spelling of 661405544 in words is "six hundred sixty-one million, four hundred five thousand, five hundred forty-four".