665698440 has 288 divisors, whose sum is σ = 2335011840. Its totient is φ = 151683840.

The previous prime is 665698417. The next prime is 665698457. The reversal of 665698440 is 44896566.

665698440 = T₃₂₁ + T₃₂₂ + ... + T₁₅₉₀.

It is a happy number.

It is a Smith number, since the sum of its digits (48) coincides with the sum of the digits of its prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 665698440.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 5241657 + ... + 5241783.

It is an arithmetic number, because the mean of its divisors is an integer number (8107680).

Almost surely, 2^665698440 is an apocalyptic number.

665698440 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 665698440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1167505920).

665698440 is an abundant number, since it is smaller than the sum of its proper divisors (1669313400).

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

665698440 is a wasteful number, since it uses less digits than its factorization.

665698440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 201 (or 167 counting only the distinct ones).

The product of its (nonzero) digits is 1244160, while the sum is 48.

The square root of 665698440 is about 25801.1325332823. The cubic root of 665698440 is about 873.1573478829.

The spelling of 665698440 in words is "six hundred sixty-five million, six hundred ninety-eight thousand, four hundred forty".