66745638 has 48 divisors (see below), whose sum is σ = 155759760. Its totient is φ = 20579328.

The previous prime is 66745633. The next prime is 66745667. The reversal of 66745638 is 83654766.

66745638 is a `hidden beast` number, since 6 + 6 + 7 + 4 + 5 + 638 = 666.

It is a junction number, because it is equal to n+sod(n) for n = 66745593 and 66745602.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66745631) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 16206 + ... + 19902.

It is an arithmetic number, because the mean of its divisors is an integer number (3244995).

Almost surely, 2^66745638 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66745638, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (77879880).

66745638 is an abundant number, since it is smaller than the sum of its proper divisors (89014122).

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

66745638 is a wasteful number, since it uses less digits than its factorization.

66745638 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3781 (or 3778 counting only the distinct ones).

The product of its digits is 725760, while the sum is 45.

The square root of 66745638 is about 8169.8003647580. The cubic root of 66745638 is about 405.6401763944.

The spelling of 66745638 in words is "sixty-six million, seven hundred forty-five thousand, six hundred thirty-eight".