1640394621 has 12 divisors (see below), whose sum is σ = 2494167520. Its totient is φ = 1036038600.

The previous prime is 1640394601. The next prime is 1640394629. The reversal of 1640394621 is 1264930461.

1640394621 is a `hidden beast` number, since 1 + 640 + 3 + 9 + 4 + 6 + 2 + 1 = 666.

It is not a de Polignac number, because 1640394621 - 2⁵ = 1640394589 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1640394629) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 4796305 + ... + 4796646.

Almost surely, 2^1640394621 is an apocalyptic number.

It is an amenable number.

1640394621 is a deficient number, since it is larger than the sum of its proper divisors (853772899).

1640394621 is a wasteful number, since it uses less digits than its factorization.

1640394621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9592976 (or 9592973 counting only the distinct ones).

The product of its (nonzero) digits is 31104, while the sum is 36.

The square root of 1640394621 is about 40501.7854050905. The cubic root of 1640394621 is about 1179.3682870284.

The spelling of 1640394621 in words is "one billion, six hundred forty million, three hundred ninety-four thousand, six hundred twenty-one".