243786640 has 20 divisors (see below), whose sum is σ = 566804124. Its totient is φ = 97514624.

The previous prime is 243786619. The next prime is 243786649. The reversal of 243786640 is 46687342.

It is a happy number.

243786640 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 181818256 + 61968384 = 13484^2 + 7872^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a Harshad number since it is a multiple of its sum of digits (40).

It is a junction number, because it is equal to n+sod(n) for n = 243786593 and 243786602.

It is not an unprimeable number, because it can be changed into a prime (243786649) 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, 1523587 + ... + 1523746.

Almost surely, 2^243786640 is an apocalyptic number.

243786640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

243786640 is an abundant number, since it is smaller than the sum of its proper divisors (323017484).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

243786640 is a wasteful number, since it uses less digits than its factorization.

243786640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3047346 (or 3047340 counting only the distinct ones).

The product of its (nonzero) digits is 193536, while the sum is 40.

The square root of 243786640 is about 15613.6683710139. The cubic root of 243786640 is about 624.6977866909.

The spelling of 243786640 in words is "two hundred forty-three million, seven hundred eighty-six thousand, six hundred forty".