661318544 has 10 divisors (see below), whose sum is σ = 1281304710. Its totient is φ = 330659264.

The previous prime is 661318481. The next prime is 661318573. The reversal of 661318544 is 445813166.

It can be written as a sum of positive squares in only one way, i.e., 661106944 + 211600 = 25712^2 + 460^2 .

It is a junction number, because it is equal to n+sod(n) for n = 661318498 and 661318507.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20666189 + ... + 20666220.

It is an arithmetic number, because the mean of its divisors is an integer number (128130471).

Almost surely, 2^661318544 is an apocalyptic number.

It is an amenable number.

661318544 is a deficient number, since it is larger than the sum of its proper divisors (619986166).

661318544 is a wasteful number, since it uses less digits than its factorization.

661318544 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41332417 (or 41332411 counting only the distinct ones).

The product of its digits is 69120, while the sum is 38.

The square root of 661318544 is about 25716.1144810020. The cubic root of 661318544 is about 871.2381823765.

The spelling of 661318544 in words is "six hundred sixty-one million, three hundred eighteen thousand, five hundred forty-four".