661643533 has 8 divisors (see below), whose sum is σ = 678507840. Its totient is φ = 644988960.

The previous prime is 661643503. The next prime is 661643539. The reversal of 661643533 is 335346166.

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 661643533 - 2¹⁷ = 661512461 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 661643492 and 661643501.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661643539) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 46035 + ... + 58672.

It is an arithmetic number, because the mean of its divisors is an integer number (84813480).

Almost surely, 2^661643533 is an apocalyptic number.

It is an amenable number.

661643533 is a deficient number, since it is larger than the sum of its proper divisors (16864307).

661643533 is a wasteful number, since it uses less digits than its factorization.

661643533 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 104867.

The product of its digits is 116640, while the sum is 37.

The square root of 661643533 is about 25722.4324860617. The cubic root of 661643533 is about 871.3808753140.

Adding to 661643533 its reverse (335346166), we get a palindrome (996989699).

The spelling of 661643533 in words is "six hundred sixty-one million, six hundred forty-three thousand, five hundred thirty-three".