1664400 has 120 divisors (see below), whose sum is σ = 5689120. Its totient is φ = 414720.

The previous prime is 1664387. The next prime is 1664407. The reversal of 1664400 is 44661.

1664400 = T₄₅ + T₄₆ + ... + T₂₁₅.

1664400 is nontrivially palindromic in base 9.

1664400 is a nontrivial binomial coefficient, being equal to C(1825, 2).

It is a tau number, because it is divible by the number of its divisors (120).

It is not an unprimeable number, because it can be changed into a prime (1664407) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 22764 + ... + 22836.

2^1664400 is an apocalyptic number.

1664400 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

1664400 is the 1824-th triangular number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1664400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2844560).

1664400 is an abundant number, since it is smaller than the sum of its proper divisors (4024720).

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

1664400 is a wasteful number, since it uses less digits than its factorization.

1664400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 113 (or 102 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 21.

The square root of 1664400 is about 1290.1162738296. The cubic root of 1664400 is about 118.5093371553.

The spelling of 1664400 in words is "one million, six hundred sixty-four thousand, four hundred".