1665643264 has 36 divisors (see below), whose sum is σ = 3332578480. Its totient is φ = 830868480.

The previous prime is 1665643241. The next prime is 1665643267. The reversal of 1665643264 is 4623465661.

It is a self number, because there is not a number n which added to its sum of digits gives 1665643264.

It is not an unprimeable number, because it can be changed into a prime (1665643267) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 104974 + ... + 119794.

Almost surely, 2^1665643264 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1665643264, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1666289240).

1665643264 is an abundant number, since it is smaller than the sum of its proper divisors (1666935216).

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

1665643264 is an equidigital number, since it uses as much as digits as its factorization.

1665643264 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15276 (or 15262 counting only the distinct ones).

The product of its digits is 622080, while the sum is 43.

The square root of 1665643264 is about 40812.2930500113. The cubic root of 1665643264 is about 1185.3883762026.

The spelling of 1665643264 in words is "one billion, six hundred sixty-five million, six hundred forty-three thousand, two hundred sixty-four".