66623440 has 120 divisors (see below), whose sum is σ = 176316840. Its totient is φ = 23245824.

The previous prime is 66623429. The next prime is 66623441. The reversal of 66623440 is 4432666.

It can be written as a sum of positive squares in 4 ways, for example, as 1272384 + 65351056 = 1128^2 + 8084^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66623441) 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, 1417497 + ... + 1417543.

It is an arithmetic number, because the mean of its divisors is an integer number (1469307).

Almost surely, 2^66623440 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 66623440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (88158420).

66623440 is an abundant number, since it is smaller than the sum of its proper divisors (109693400).

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

66623440 is a wasteful number, since it uses less digits than its factorization.

66623440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 149 (or 96 counting only the distinct ones).

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

The square root of 66623440 is about 8162.3182981307. The cubic root of 66623440 is about 405.3924763172.

The spelling of 66623440 in words is "sixty-six million, six hundred twenty-three thousand, four hundred forty".