661749 has 12 divisors (see below), whose sum is σ = 970368. Its totient is φ = 400840.

The previous prime is 661741. The next prime is 661769. The reversal of 661749 is 947166.

It is a happy number.

661749 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 661749 - 2³ = 661741 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a Curzon 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 11 ways as a sum of consecutive naturals, for example, 549 + ... + 1274.

It is an arithmetic number, because the mean of its divisors is an integer number (80864).

2⁶⁶¹⁷⁴⁹ is an apocalyptic number.

It is an amenable number.

661749 is a deficient number, since it is larger than the sum of its proper divisors (308619).

661749 is a wasteful number, since it uses less digits than its factorization.

661749 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1848 (or 1837 counting only the distinct ones).

The product of its digits is 9072, while the sum is 33.

The square root of 661749 is about 813.4795633573. The cubic root of 661749 is about 87.1427172673.

It can be divided in two parts, 6617 and 49, that added together give a palindrome (6666).

The spelling of 661749 in words is "six hundred sixty-one thousand, seven hundred forty-nine".