1640685605 has 16 divisors (see below), whose sum is σ = 2122120560. Its totient is φ = 1210526208.

The previous prime is 1640685601. The next prime is 1640685617. The reversal of 1640685605 is 5065860461.

It is a happy number.

It can be written as a sum of positive squares in 8 ways, for example, as 660181636 + 980503969 = 25694^2 + 31313^2 .

It is a cyclic number.

It is not a de Polignac number, because 1640685605 - 2² = 1640685601 is a prime.

It is a super-3 number, since 3×1640685605³ (a number of 29 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1640685601) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 68441 + ... + 89249.

It is an arithmetic number, because the mean of its divisors is an integer number (132632535).

Almost surely, 2^1640685605 is an apocalyptic number.

It is an amenable number.

1640685605 is a deficient number, since it is larger than the sum of its proper divisors (481434955).

1640685605 is a wasteful number, since it uses less digits than its factorization.

1640685605 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22040.

The product of its (nonzero) digits is 172800, while the sum is 41.

The square root of 1640685605 is about 40505.3774825022. The cubic root of 1640685605 is about 1179.4380176098.

The spelling of 1640685605 in words is "one billion, six hundred forty million, six hundred eighty-five thousand, six hundred five".