1640538217 has 2 divisors, whose sum is σ = 1640538218. Its totient is φ = 1640538216.

The previous prime is 1640538191. The next prime is 1640538239. The reversal of 1640538217 is 7128350461.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1442404441 + 198133776 = 37979^2 + 14076^2 .

It is a cyclic number.

It is not a de Polignac number, because 1640538217 - 2¹⁹ = 1640013929 is a prime.

It is not a weakly prime, because it can be changed into another prime (1640538257) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 820269108 + 820269109.

It is an arithmetic number, because the mean of its divisors is an integer number (820269109).

Almost surely, 2^1640538217 is an apocalyptic number.

It is an amenable number.

1640538217 is a deficient number, since it is larger than the sum of its proper divisors (1).

1640538217 is an equidigital number, since it uses as much as digits as its factorization.

1640538217 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 40320, while the sum is 37.

The square root of 1640538217 is about 40503.5580782726. The cubic root of 1640538217 is about 1179.4026989976.

Adding to 1640538217 its reverse (7128350461), we get a palindrome (8768888678).

The spelling of 1640538217 in words is "one billion, six hundred forty million, five hundred thirty-eight thousand, two hundred seventeen".