243400661 has 4 divisors (see below), whose sum is σ = 278172192. Its totient is φ = 208629132.

The previous prime is 243400657. The next prime is 243400673. The reversal of 243400661 is 166004342.

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 243400661 - 2² = 243400657 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 243400661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (243400631) 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, 17385755 + ... + 17385768.

It is an arithmetic number, because the mean of its divisors is an integer number (69543048).

Almost surely, 2^243400661 is an apocalyptic number.

It is an amenable number.

243400661 is a deficient number, since it is larger than the sum of its proper divisors (34771531).

243400661 is an equidigital number, since it uses as much as digits as its factorization.

243400661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 34771530.

The product of its (nonzero) digits is 3456, while the sum is 26.

The square root of 243400661 is about 15601.3031827473. The cubic root of 243400661 is about 624.3679250388.

The spelling of 243400661 in words is "two hundred forty-three million, four hundred thousand, six hundred sixty-one".