1289520640 has 80 divisors (see below), whose sum is σ = 3191760000. Its totient is φ = 499138560.

The previous prime is 1289520637. The next prime is 1289520667. The reversal of 1289520640 is 460259821.

It is a tau number, because it is divible by the number of its divisors (80).

It is a self number, because there is not a number n which added to its sum of digits gives 1289520640.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 71236 + ... + 87484.

It is an arithmetic number, because the mean of its divisors is an integer number (39897000).

Almost surely, 2^1289520640 is an apocalyptic number.

1289520640 is a gapful number since it is divisible by the number (10) 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 1289520640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1595880000).

1289520640 is an abundant number, since it is smaller than the sum of its proper divisors (1902239360).

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

1289520640 is an equidigital number, since it uses as much as digits as its factorization.

1289520640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16303 (or 16287 counting only the distinct ones).

The product of its (nonzero) digits is 34560, while the sum is 37.

The square root of 1289520640 is about 35909.8961290617. The cubic root of 1289520640 is about 1088.4523782008.

The spelling of 1289520640 in words is "one billion, two hundred eighty-nine million, five hundred twenty thousand, six hundred forty".