661543144 has 8 divisors (see below), whose sum is σ = 1240393410. Its totient is φ = 330771568.

The previous prime is 661543123. The next prime is 661543171. The reversal of 661543144 is 441345166.

It can be written as a sum of positive squares in only one way, i.e., 385651044 + 275892100 = 19638^2 + 16610^2 .

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, 41346439 + ... + 41346454.

Almost surely, 2^661543144 is an apocalyptic number.

It is an amenable number.

661543144 is a deficient number, since it is larger than the sum of its proper divisors (578850266).

661543144 is a wasteful number, since it uses less digits than its factorization.

661543144 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 82692899 (or 82692895 counting only the distinct ones).

The product of its digits is 34560, while the sum is 34.

The square root of 661543144 is about 25720.4810219405. The cubic root of 661543144 is about 871.3368024989.

The spelling of 661543144 in words is "six hundred sixty-one million, five hundred forty-three thousand, one hundred forty-four".