1664621 has 8 divisors (see below), whose sum is σ = 1910400. Its totient is φ = 1420848.

The previous prime is 1664569. The next prime is 1664627. The reversal of 1664621 is 1264661.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1664621 - 2⁶ = 1664557 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1664627) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2480 + ... + 3078.

It is an arithmetic number, because the mean of its divisors is an integer number (238800).

2^1664621 is an apocalyptic number.

It is an amenable number.

1664621 is a deficient number, since it is larger than the sum of its proper divisors (245779).

1664621 is an equidigital number, since it uses as much as digits as its factorization.

1664621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1003.

The product of its digits is 1728, while the sum is 26.

The square root of 1664621 is about 1290.2019221812. The cubic root of 1664621 is about 118.5145821694.

The spelling of 1664621 in words is "one million, six hundred sixty-four thousand, six hundred twenty-one".