243942921 has 10 divisors (see below), whose sum is σ = 364408682. Its totient is φ = 162628560.

The previous prime is 243942917. The next prime is 243942943. The reversal of 243942921 is 129249342.

It can be written as a sum of positive squares in only one way, i.e., 201952521 + 41990400 = 14211^2 + 6480^2 .

It is not a de Polignac number, because 243942921 - 2² = 243942917 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (243942901) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 1505740 + ... + 1505901.

Almost surely, 2^243942921 is an apocalyptic number.

It is an amenable number.

243942921 is a deficient number, since it is larger than the sum of its proper divisors (120465761).

243942921 is an equidigital number, since it uses as much as digits as its factorization.

243942921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3011653 (or 3011644 counting only the distinct ones).

The product of its digits is 31104, while the sum is 36.

The square root of 243942921 is about 15618.6721906825. The cubic root of 243942921 is about 624.8312470267.

The spelling of 243942921 in words is "two hundred forty-three million, nine hundred forty-two thousand, nine hundred twenty-one".