1640908643 has 8 divisors (see below), whose sum is σ = 1790386416. Its totient is φ = 1491481600.

The previous prime is 1640908639. The next prime is 1640908657. The reversal of 1640908643 is 3468090461.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1640908643 - 2² = 1640908639 is a prime.

It is a Duffinian number.

It is a zygodrome in base 7.

It is a self number, because there is not a number n which added to its sum of digits gives 1640908643.

It is not an unprimeable number, because it can be changed into a prime (1640908693) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 94055 + ... + 110127.

It is an arithmetic number, because the mean of its divisors is an integer number (223798302).

Almost surely, 2^1640908643 is an apocalyptic number.

1640908643 is a deficient number, since it is larger than the sum of its proper divisors (149477773).

1640908643 is a wasteful number, since it uses less digits than its factorization.

1640908643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25365.

The product of its (nonzero) digits is 124416, while the sum is 41.

The square root of 1640908643 is about 40508.1305789344. The cubic root of 1640908643 is about 1179.4914602228.

The spelling of 1640908643 in words is "one billion, six hundred forty million, nine hundred eight thousand, six hundred forty-three".