66523644 has 72 divisors (see below), whose sum is σ = 189396480. Its totient is φ = 19504800.

The previous prime is 66523643. The next prime is 66523649. The reversal of 66523644 is 44632566.

66523644 is a `hidden beast` number, since 6 + 6 + 5 + 2 + 3 + 644 = 666.

It is a super-2 number, since 2×66523644² = 8850790422077472, which contains 22 as substring.

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

It is a junction number, because it is equal to n+sod(n) for n = 66523599 and 66523608.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66523643) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 9567 + ... + 14985.

Almost surely, 2^66523644 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 66523644, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (94698240).

66523644 is an abundant number, since it is smaller than the sum of its proper divisors (122872836).

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

66523644 is a wasteful number, since it uses less digits than its factorization.

66523644 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5471 (or 5466 counting only the distinct ones).

The product of its digits is 103680, while the sum is 36.

The square root of 66523644 is about 8156.2027929668. The cubic root of 66523644 is about 405.1899611839.

It can be divided in two parts, 6652 and 3644, that added together give a triangular number (10296 = T₁₄₃).

The spelling of 66523644 in words is "sixty-six million, five hundred twenty-three thousand, six hundred forty-four".