669138624 has 448 divisors, whose sum is σ = 2528133120. Its totient is φ = 168514560.

The previous prime is 669138623. The next prime is 669138661. The reversal of 669138624 is 426831966.

669138624 is a `hidden beast` number, since 6 + 6 + 9 + 13 + 8 + 624 = 666.

669138624 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (448).

It is a super-3 number, since 3×669138624³ (a number of 27 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

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

It is a self number, because there is not a number n which added to its sum of digits gives 669138624.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (669138623) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 6253579 + ... + 6253685.

Almost surely, 2^669138624 is an apocalyptic number.

669138624 is a gapful number since it is divisible by the number (64) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 669138624, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1264066560).

669138624 is an abundant number, since it is smaller than the sum of its proper divisors (1858994496).

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

669138624 is a wasteful number, since it uses less digits than its factorization.

669138624 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 193 (or 177 counting only the distinct ones).

The product of its digits is 373248, while the sum is 45.

The square root of 669138624 is about 25867.7139306897. The cubic root of 669138624 is about 874.6588597773.

The spelling of 669138624 in words is "six hundred sixty-nine million, one hundred thirty-eight thousand, six hundred twenty-four".