1289664 has 42 divisors (see below), whose sum is σ = 3698240. Its totient is φ = 429696.

The previous prime is 1289657. The next prime is 1289677. The reversal of 1289664 is 4669821.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 544 + ... + 1695.

2^1289664 is an apocalyptic number.

It is an amenable number.

1289664 is an abundant number, since it is smaller than the sum of its proper divisors (2408576).

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

1289664 is a wasteful number, since it uses less digits than its factorization.

1289664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2257 (or 2244 counting only the distinct ones).

The product of its digits is 20736, while the sum is 36.

The square root of 1289664 is about 1135.6337437748. The cubic root of 1289664 is about 108.8492712246.

It can be divided in two parts, 1289 and 664, that added together give a triangular number (1953 = T₆₂).

The spelling of 1289664 in words is "one million, two hundred eighty-nine thousand, six hundred sixty-four".