243031661 has 4 divisors (see below), whose sum is σ = 250871424. Its totient is φ = 235191900.

The previous prime is 243031597. The next prime is 243031697. The reversal of 243031661 is 166130342.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 243031661 - 2⁶ = 243031597 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 243031661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (243331661) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3919835 + ... + 3919896.

It is an arithmetic number, because the mean of its divisors is an integer number (62717856).

Almost surely, 2^243031661 is an apocalyptic number.

It is an amenable number.

243031661 is a deficient number, since it is larger than the sum of its proper divisors (7839763).

243031661 is an equidigital number, since it uses as much as digits as its factorization.

243031661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7839762.

The product of its (nonzero) digits is 2592, while the sum is 26.

The square root of 243031661 is about 15589.4727620917. The cubic root of 243031661 is about 624.0522476044.

The spelling of 243031661 in words is "two hundred forty-three million, thirty-one thousand, six hundred sixty-one".