1640831220 has 144 divisors (see below), whose sum is σ = 5766458880. Its totient is φ = 369888768.

The previous prime is 1640831167. The next prime is 1640831221. The reversal of 1640831220 is 221380461.

1640831220 is a `hidden beast` number, since 1 + 6 + 408 + 31 + 220 = 666.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1640831221) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 83061 + ... + 100899.

Almost surely, 2^1640831220 is an apocalyptic number.

1640831220 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1640831220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2883229440).

1640831220 is an abundant number, since it is smaller than the sum of its proper divisors (4125627660).

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

1640831220 is a wasteful number, since it uses less digits than its factorization.

1640831220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17934 (or 17929 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 27.

The square root of 1640831220 is about 40507.1749200065. The cubic root of 1640831220 is about 1179.4729092807.

The spelling of 1640831220 in words is "one billion, six hundred forty million, eight hundred thirty-one thousand, two hundred twenty".