661672 has 32 divisors (see below), whose sum is σ = 1385280. Its totient is φ = 293760.

The previous prime is 661663. The next prime is 661673. The reversal of 661672 is 276166.

Its product of digits (3024) is a multiple of the sum of its prime divisors (189).

It is a self number, because there is not a number n which added to its sum of digits gives 661672.

It is not an unprimeable number, because it can be changed into a prime (661673) by changing a digit.

661672 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6373 + ... + 6475.

It is an arithmetic number, because the mean of its divisors is an integer number (43290).

2⁶⁶¹⁶⁷² is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 661672, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (692640).

661672 is an abundant number, since it is smaller than the sum of its proper divisors (723608).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

661672 is a wasteful number, since it uses less digits than its factorization.

661672 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 193 (or 189 counting only the distinct ones).

The product of its digits is 3024, while the sum is 28.

The square root of 661672 is about 813.4322344240. The cubic root of 661672 is about 87.1393372095.

The spelling of 661672 in words is "six hundred sixty-one thousand, six hundred seventy-two".