1644012220 has 36 divisors (see below), whose sum is σ = 3510109512. Its totient is φ = 646795200.

The previous prime is 1644012203. The next prime is 1644012263. The reversal of 1644012220 is 222104461.

It is a happy number.

It is a super-3 number, since 3×1644012220³ (a number of 29 digits) contains 333 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 1644012191 and 1644012200.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 63375 + ... + 85465.

It is an arithmetic number, because the mean of its divisors is an integer number (97503042).

Almost surely, 2^1644012220 is an apocalyptic number.

1644012220 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1644012220 is an abundant number, since it is smaller than the sum of its proper divisors (1866097292).

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

1644012220 is a wasteful number, since it uses less digits than its factorization.

1644012220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22222 (or 22159 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 22.

The square root of 1644012220 is about 40546.4205571836. The cubic root of 1644012220 is about 1180.2346129307.

Adding to 1644012220 its reverse (222104461), we get a palindrome (1866116681).

The spelling of 1644012220 in words is "one billion, six hundred forty-four million, twelve thousand, two hundred twenty".