661243844 has 6 divisors (see below), whose sum is σ = 1157176734. Its totient is φ = 330621920.

The previous prime is 661243831. The next prime is 661243879. The reversal of 661243844 is 448342166.

It can be written as a sum of positive squares in only one way, i.e., 661106944 + 136900 = 25712^2 + 370^2 .

It is a junction number, because it is equal to n+sod(n) for n = 661243798 and 661243807.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82655477 + ... + 82655484.

It is an arithmetic number, because the mean of its divisors is an integer number (192862789).

Almost surely, 2^661243844 is an apocalyptic number.

It is an amenable number.

661243844 is a deficient number, since it is larger than the sum of its proper divisors (495932890).

661243844 is a wasteful number, since it uses less digits than its factorization.

661243844 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 165310965 (or 165310963 counting only the distinct ones).

The product of its digits is 110592, while the sum is 38.

The square root of 661243844 is about 25714.6620432780. The cubic root of 661243844 is about 871.2053772362.

The spelling of 661243844 in words is "six hundred sixty-one million, two hundred forty-three thousand, eight hundred forty-four".