661624 has 16 divisors (see below), whose sum is σ = 1249920. Its totient is φ = 328320.

The previous prime is 661621. The next prime is 661663. The reversal of 661624 is 426166.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661621) 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, 1312 + ... + 1744.

It is an arithmetic number, because the mean of its divisors is an integer number (78120).

2⁶⁶¹⁶²⁴ is an apocalyptic number.

It is an amenable number.

661624 is a deficient number, since it is larger than the sum of its proper divisors (588296).

661624 is a wasteful number, since it uses less digits than its factorization.

661624 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 630 (or 626 counting only the distinct ones).

The product of its digits is 1728, while the sum is 25.

The square root of 661624 is about 813.4027292799. The cubic root of 661624 is about 87.1372300279.

It can be divided in two parts, 66162 and 4, that added together give a palindrome (66166).

The spelling of 661624 in words is "six hundred sixty-one thousand, six hundred twenty-four".