66643540 has 24 divisors (see below), whose sum is σ = 140388192. Its totient is φ = 26574240.

The previous prime is 66643523. The next prime is 66643541. The reversal of 66643540 is 4534666.

It is a super-2 number, since 2×66643540² = 8882722847463200, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 66643496 and 66643505.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66643541) 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, 1587 + ... + 11653.

It is an arithmetic number, because the mean of its divisors is an integer number (5849508).

Almost surely, 2^66643540 is an apocalyptic number.

It is an amenable number.

66643540 is an abundant number, since it is smaller than the sum of its proper divisors (73744652).

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

66643540 is a wasteful number, since it uses less digits than its factorization.

66643540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10407 (or 10405 counting only the distinct ones).

The product of its (nonzero) digits is 51840, while the sum is 34.

The square root of 66643540 is about 8163.5494731152. The cubic root of 66643540 is about 405.4332405961.

The spelling of 66643540 in words is "sixty-six million, six hundred forty-three thousand, five hundred forty".