1640221 has 4 divisors (see below), whose sum is σ = 1789344. Its totient is φ = 1491100.

The previous prime is 1640207. The next prime is 1640231. The reversal of 1640221 is 1220461.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 1220461 = 11 ⋅110951.

It is a cyclic number.

It is not a de Polignac number, because 1640221 - 2⁵ = 1640189 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1640195 and 1640204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1640201) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 74545 + ... + 74566.

It is an arithmetic number, because the mean of its divisors is an integer number (447336).

2^1640221 is an apocalyptic number.

1640221 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1640221 is a deficient number, since it is larger than the sum of its proper divisors (149123).

1640221 is a wasteful number, since it uses less digits than its factorization.

1640221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 149122.

The product of its (nonzero) digits is 96, while the sum is 16.

The square root of 1640221 is about 1280.7111305833. The cubic root of 1640221 is about 117.9326677056.

Adding to 1640221 its reverse (1220461), we get a palindrome (2860682).

The spelling of 1640221 in words is "one million, six hundred forty thousand, two hundred twenty-one".