1640436220 has 12 divisors (see below), whose sum is σ = 3444916104. Its totient is φ = 656174480.

The previous prime is 1640436191. The next prime is 1640436223. The reversal of 1640436220 is 226340461.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1640436223) 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, 41010886 + ... + 41010925.

It is an arithmetic number, because the mean of its divisors is an integer number (287076342).

Almost surely, 2^1640436220 is an apocalyptic number.

1640436220 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1640436220 is an abundant number, since it is smaller than the sum of its proper divisors (1804479884).

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

1640436220 is a wasteful number, since it uses less digits than its factorization.

1640436220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 82021820 (or 82021818 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 28.

The square root of 1640436220 is about 40502.2989470968. The cubic root of 1640436220 is about 1179.3782562001.

Adding to 1640436220 its reverse (226340461), we get a palindrome (1866776681).

The spelling of 1640436220 in words is "one billion, six hundred forty million, four hundred thirty-six thousand, two hundred twenty".