1664215 has 16 divisors (see below), whose sum is σ = 2417472. Its totient is φ = 1073664.

The previous prime is 1664123. The next prime is 1664227. The reversal of 1664215 is 5124661.

It is a cyclic number.

It is not a de Polignac number, because 1664215 - 2⁹ = 1663703 is a prime.

It is a super-2 number, since 2×1664215² = 5539223132450, which contains 22 as substring.

It is a Duffinian number.

1664215 is a lucky number.

It is a self number, because there is not a number n which added to its sum of digits gives 1664215.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 804 + ... + 1993.

It is an arithmetic number, because the mean of its divisors is an integer number (151092).

2^1664215 is an apocalyptic number.

1664215 is a deficient number, since it is larger than the sum of its proper divisors (753257).

1664215 is a wasteful number, since it uses less digits than its factorization.

1664215 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2826.

The product of its digits is 1440, while the sum is 25.

The square root of 1664215 is about 1290.0445728734. The cubic root of 1664215 is about 118.5049461756.

Adding to 1664215 its reverse (5124661), we get a palindrome (6788876).

The spelling of 1664215 in words is "one million, six hundred sixty-four thousand, two hundred fifteen".