1642664221 has 16 divisors (see below), whose sum is σ = 1847938176. Its totient is φ = 1447200000.

The previous prime is 1642664207. The next prime is 1642664227. The reversal of 1642664221 is 1224662461.

It is a cyclic number.

It is not a de Polignac number, because 1642664221 - 2²³ = 1634275613 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 (1642664227) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 56041 + ... + 80161.

It is an arithmetic number, because the mean of its divisors is an integer number (115496136).

Almost surely, 2^1642664221 is an apocalyptic number.

1642664221 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1642664221 is a deficient number, since it is larger than the sum of its proper divisors (205273955).

1642664221 is a wasteful number, since it uses less digits than its factorization.

1642664221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24324.

The product of its digits is 27648, while the sum is 34.

The square root of 1642664221 is about 40529.7942383131. The cubic root of 1642664221 is about 1179.9119490461.

The spelling of 1642664221 in words is "one billion, six hundred forty-two million, six hundred sixty-four thousand, two hundred twenty-one".