661543231 has 8 divisors (see below), whose sum is σ = 676850528. Its totient is φ = 646380000.

The previous prime is 661543217. The next prime is 661543237. The reversal of 661543231 is 132345166.

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 661543231 - 2¹⁵ = 661510463 is a prime.

It is a super-2 number, since 2×661543231² = 875278892963838722, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 661543193 and 661543202.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661543237) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 26700 + ... + 45121.

It is an arithmetic number, because the mean of its divisors is an integer number (84606316).

Almost surely, 2^661543231 is an apocalyptic number.

661543231 is a gapful number since it is divisible by the number (61) formed by its first and last digit.

661543231 is a deficient number, since it is larger than the sum of its proper divisors (15307297).

661543231 is a wasteful number, since it uses less digits than its factorization.

661543231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 72033.

The product of its digits is 12960, while the sum is 31.

The square root of 661543231 is about 25720.4827131996. The cubic root of 661543231 is about 871.3368406956.

Adding to 661543231 its reverse (132345166), we get a palindrome (793888397).

The spelling of 661543231 in words is "six hundred sixty-one million, five hundred forty-three thousand, two hundred thirty-one".