661424 has 20 divisors (see below), whose sum is σ = 1302744. Its totient is φ = 325248.

The previous prime is 661421. The next prime is 661439. The reversal of 661424 is 424166.

It is a happy number.

It is an Ulam number.

It is a self number, because there is not a number n which added to its sum of digits gives 661424.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 661424.

It is not an unprimeable number, because it can be changed into a prime (661421) 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, 764 + ... + 1380.

2⁶⁶¹⁴²⁴ is an apocalyptic number.

It is an amenable number.

661424 is a deficient number, since it is larger than the sum of its proper divisors (641320).

661424 is a wasteful number, since it uses less digits than its factorization.

661424 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 692 (or 686 counting only the distinct ones).

The product of its digits is 1152, while the sum is 23.

The square root of 661424 is about 813.2797796577. The cubic root of 661424 is about 87.1284490071.

The spelling of 661424 in words is "six hundred sixty-one thousand, four hundred twenty-four".