66243640 has 32 divisors (see below), whose sum is σ = 151865280. Its totient is φ = 25996672.

The previous prime is 66243629. The next prime is 66243641. The reversal of 66243640 is 4634266.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66243641) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13504 + ... + 17743.

It is an arithmetic number, because the mean of its divisors is an integer number (4745790).

Almost surely, 2^66243640 is an apocalyptic number.

It is an amenable number.

66243640 is an abundant number, since it is smaller than the sum of its proper divisors (85621640).

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

66243640 is a wasteful number, since it uses less digits than its factorization.

66243640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31311 (or 31307 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 31.

The square root of 66243640 is about 8139.0195969785. The cubic root of 66243640 is about 404.6206680382.

The spelling of 66243640 in words is "sixty-six million, two hundred forty-three thousand, six hundred forty".