664213440 has 224 divisors, whose sum is σ = 2375976960. Its totient is φ = 155750400.

The previous prime is 664213373. The next prime is 664213483. The reversal of 664213440 is 44312466.

664213440 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 664213398 and 664213407.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 326346 + ... + 328374.

It is an arithmetic number, because the mean of its divisors is an integer number (10607040).

Almost surely, 2^664213440 is an apocalyptic number.

664213440 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

664213440 is the 14880-th octagonal number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 664213440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1187988480).

664213440 is an abundant number, since it is smaller than the sum of its proper divisors (1711763520).

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

664213440 is a wasteful number, since it uses less digits than its factorization.

664213440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2091 (or 2081 counting only the distinct ones).

The product of its (nonzero) digits is 13824, while the sum is 30.

The square root of 664213440 is about 25772.3386598888. The cubic root of 664213440 is about 872.5076022249.

The spelling of 664213440 in words is "six hundred sixty-four million, two hundred thirteen thousand, four hundred forty".