661632 has 32 divisors (see below), whose sum is σ = 1758480. Its totient is φ = 220416.

The previous prime is 661621. The next prime is 661663. The reversal of 661632 is 236166.

It is a tau number, because it is divible by the number of its divisors (32).

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a nude number because it is divisible by every one of its digits.

It is an unprimeable number.

661632 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 (5) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 478 + ... + 1245.

2⁶⁶¹⁶³² is an apocalyptic number.

It is an amenable number.

661632 is an abundant number, since it is smaller than the sum of its proper divisors (1096848).

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

661632 is a wasteful number, since it uses less digits than its factorization.

661632 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1740 (or 1728 counting only the distinct ones).

The product of its digits is 1296, while the sum is 24.

The square root of 661632 is about 813.4076468782. The cubic root of 661632 is about 87.1375812319.

Adding to 661632 its reverse (236166), we get a palindrome (897798).

The spelling of 661632 in words is "six hundred sixty-one thousand, six hundred thirty-two".