243617661 has 72 divisors (see below), whose sum is σ = 434285280.
Its totient is φ = 130987584.
The previous prime is 243617651. The next prime is 243617669. The reversal of 243617661 is 166716342.
It is a happy number.
It is not a de Polignac number, because 243617661 - 215 = 243584893 is a prime.
It is a super-2 number, since 2×2436176612 = 118699129502221842, which contains 22 as substring.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (243617669) by changing a digit.
It is a pernicious number, because its binary representation contains a prime number (17) of ones.
It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 549706 + ... + 550148.
It is an arithmetic number, because the mean of its divisors is an integer number (6031740).
Almost surely, 2243617661 is an apocalyptic number.
243617661 is a gapful number since it is divisible by the number (21) formed by its first and last digit.
It is an amenable number.
243617661 is a deficient number, since it is larger than the sum of its proper divisors (190667619).
243617661 is a wasteful number, since it uses less digits than its factorization.
243617661 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 535 (or 525 counting only the distinct ones).
The product of its digits is 36288, while the sum is 36.
The square root of 243617661 is about 15608.2561806244.
The cubic root of 243617661 is about 624.5534183664.
The spelling of 243617661 in words is "two hundred forty-three million, six hundred seventeen thousand, six hundred sixty-one".