664899840 has 540 divisors, whose sum is σ = 2664421452. Its totient is φ = 158146560.

The previous prime is 664899773. The next prime is 664899853. The reversal of 664899840 is 48998466.

It can be written as a sum of positive squares in 2 ways, for example, as 361304064 + 303595776 = 19008^2 + 17424^2 .

It is a tau number, because it is divible by the number of its divisors (540).

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 59 ways as a sum of consecutive naturals, for example, 12545254 + ... + 12545306.

Almost surely, 2^664899840 is an apocalyptic number.

664899840 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 664899840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1332210726).

664899840 is an abundant number, since it is smaller than the sum of its proper divisors (1999521612).

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

664899840 is a wasteful number, since it uses less digits than its factorization.

664899840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 108 (or 74 counting only the distinct ones).

The product of its (nonzero) digits is 2985984, while the sum is 54.

The square root of 664899840 is about 25785.6518242219. The cubic root of 664899840 is about 872.8080493415.

It can be divided in two parts, 6 and 64899840, that added together give a palindrome (64899846).

The spelling of 664899840 in words is "six hundred sixty-four million, eight hundred ninety-nine thousand, eight hundred forty".