1640908644 has 24 divisors (see below), whose sum is σ = 3830299200. Its totient is φ = 546753504.

The previous prime is 1640908639. The next prime is 1640908657. The reversal of 1640908644 is 4468090461.

It is a junction number, because it is equal to n+sod(n) for n = 1640908596 and 1640908605.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6282 + ... + 57630.

It is an arithmetic number, because the mean of its divisors is an integer number (159595800).

Almost surely, 2^1640908644 is an apocalyptic number.

It is an amenable number.

1640908644 is an abundant number, since it is smaller than the sum of its proper divisors (2189390556).

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

1640908644 is a wasteful number, since it uses less digits than its factorization.

1640908644 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 54019 (or 54017 counting only the distinct ones).

The product of its (nonzero) digits is 165888, while the sum is 42.

The square root of 1640908644 is about 40508.1305912776. The cubic root of 1640908644 is about 1179.4914604624.

The spelling of 1640908644 in words is "one billion, six hundred forty million, nine hundred eight thousand, six hundred forty-four".