66138912 has 144 divisors (see below), whose sum is σ = 219360960. Its totient is φ = 18510336.

The previous prime is 66138899. The next prime is 66138913. The reversal of 66138912 is 21983166.

It is a tau number, because it is divible by the number of its divisors (144).

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a nude number because it is divisible by every one of its digits.

It is not an unprimeable number, because it can be changed into a prime (66138913) 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, 106539 + ... + 107157.

It is an arithmetic number, because the mean of its divisors is an integer number (1523340).

Almost surely, 2^66138912 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66138912, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (109680480).

66138912 is an abundant number, since it is smaller than the sum of its proper divisors (153222048).

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

66138912 is a wasteful number, since it uses less digits than its factorization.

66138912 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 695 (or 684 counting only the distinct ones).

The product of its digits is 15552, while the sum is 36.

The square root of 66138912 is about 8132.5833534001. The cubic root of 66138912 is about 404.4073269841.

The spelling of 66138912 in words is "sixty-six million, one hundred thirty-eight thousand, nine hundred twelve".