1640908657 has 2 divisors, whose sum is σ = 1640908658. Its totient is φ = 1640908656.

The previous prime is 1640908639. The next prime is 1640908667. The reversal of 1640908657 is 7568090461.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1039482081 + 601426576 = 32241^2 + 24524^2 .

It is a cyclic number.

It is not a de Polignac number, because 1640908657 - 2¹¹ = 1640906609 is a prime.

It is not a weakly prime, because it can be changed into another prime (1640908627) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 820454328 + 820454329.

It is an arithmetic number, because the mean of its divisors is an integer number (820454329).

Almost surely, 2^1640908657 is an apocalyptic number.

It is an amenable number.

1640908657 is a deficient number, since it is larger than the sum of its proper divisors (1).

1640908657 is an equidigital number, since it uses as much as digits as its factorization.

1640908657 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 362880, while the sum is 46.

The square root of 1640908657 is about 40508.1307517392. The cubic root of 1640908657 is about 1179.4914635772.

The spelling of 1640908657 in words is "one billion, six hundred forty million, nine hundred eight thousand, six hundred fifty-seven".