661744 has 20 divisors (see below), whose sum is σ = 1305720. Its totient is φ = 324800.

The previous prime is 661741. The next prime is 661769. The reversal of 661744 is 447166.

It is an Ulam number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661741) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 594 + ... + 1294.

It is an arithmetic number, because the mean of its divisors is an integer number (65286).

2⁶⁶¹⁷⁴⁴ is an apocalyptic number.

It is an amenable number.

661744 is a deficient number, since it is larger than the sum of its proper divisors (643976).

661744 is a wasteful number, since it uses less digits than its factorization.

661744 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 768 (or 762 counting only the distinct ones).

The product of its digits is 4032, while the sum is 28.

The square root of 661744 is about 813.4764901336. The cubic root of 661744 is about 87.1424977910.

The spelling of 661744 in words is "six hundred sixty-one thousand, seven hundred forty-four".