669581640 has 384 divisors, whose sum is σ = 2781192960. Its totient is φ = 141087744.

The previous prime is 669581597. The next prime is 669581663. The reversal of 669581640 is 46185966.

669581640 is a `hidden beast` number, since 6 + 6 + 9 + 581 + 64 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 884142 + ... + 884898.

It is an arithmetic number, because the mean of its divisors is an integer number (7242690).

Almost surely, 2^669581640 is an apocalyptic number.

669581640 is a gapful number since it is divisible by the number (60) 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 669581640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1390596480).

669581640 is an abundant number, since it is smaller than the sum of its proper divisors (2111611320).

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

669581640 is a wasteful number, since it uses less digits than its factorization.

669581640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 803 (or 787 counting only the distinct ones).

The product of its (nonzero) digits is 311040, while the sum is 45.

The square root of 669581640 is about 25876.2756207303. The cubic root of 669581640 is about 874.8518453921.

The spelling of 669581640 in words is "six hundred sixty-nine million, five hundred eighty-one thousand, six hundred forty".