243721957 has 4 divisors (see below), whose sum is σ = 243795916. Its totient is φ = 243648000.

The previous prime is 243721943. The next prime is 243721967. The reversal of 243721957 is 759127342.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 69455556 + 174266401 = 8334^2 + 13201^2 .

It is a cyclic number.

It is not a de Polignac number, because 243721957 - 2¹¹ = 243719909 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (243721927) 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, 31794 + ... + 38707.

It is an arithmetic number, because the mean of its divisors is an integer number (60948979).

Almost surely, 2^243721957 is an apocalyptic number.

It is an amenable number.

243721957 is a deficient number, since it is larger than the sum of its proper divisors (73959).

243721957 is an equidigital number, since it uses as much as digits as its factorization.

243721957 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 73958.

The product of its digits is 105840, while the sum is 40.

The square root of 243721957 is about 15611.5968754000. The cubic root of 243721957 is about 624.6425322258.

The spelling of 243721957 in words is "two hundred forty-three million, seven hundred twenty-one thousand, nine hundred fifty-seven".