661633 has 8 divisors (see below), whose sum is σ = 780800. Its totient is φ = 548640.

The previous prime is 661621. The next prime is 661663. The reversal of 661633 is 336166.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 661633 - 2⁹ = 661121 is a prime.

It is a Duffinian number.

661633 is a lucky number.

It is a junction number, because it is equal to n+sod(n) for n = 661598 and 661607.

It is not an unprimeable number, because it can be changed into a prime (661603) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1308 + ... + 1741.

It is an arithmetic number, because the mean of its divisors is an integer number (97600).

2⁶⁶¹⁶³³ is an apocalyptic number.

It is an amenable number.

661633 is a deficient number, since it is larger than the sum of its proper divisors (119167).

661633 is a wasteful number, since it uses less digits than its factorization.

661633 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3087.

The product of its digits is 1944, while the sum is 25.

The square root of 661633 is about 813.4082615759. The cubic root of 661633 is about 87.1376251322.

Adding to 661633 its reverse (336166), we get a palindrome (997799).

It can be divided in two parts, 66163 and 3, that added together give a palindrome (66166).

The spelling of 661633 in words is "six hundred sixty-one thousand, six hundred thirty-three".