1640538257 has 2 divisors, whose sum is σ = 1640538258. Its totient is φ = 1640538256.

The previous prime is 1640538239. The next prime is 1640538313. The reversal of 1640538257 is 7528350461.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1377968641 + 262569616 = 37121^2 + 16204^2 .

It is a cyclic number.

It is not a de Polignac number, because 1640538257 - 2¹⁶ = 1640472721 is a prime.

It is not a weakly prime, because it can be changed into another prime (1640538217) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 820269128 + 820269129.

It is an arithmetic number, because the mean of its divisors is an integer number (820269129).

Almost surely, 2^1640538257 is an apocalyptic number.

It is an amenable number.

1640538257 is a deficient number, since it is larger than the sum of its proper divisors (1).

1640538257 is an equidigital number, since it uses as much as digits as its factorization.

1640538257 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 201600, while the sum is 41.

The square root of 1640538257 is about 40503.5585720564. The cubic root of 1640538257 is about 1179.4027085831.

The spelling of 1640538257 in words is "one billion, six hundred forty million, five hundred thirty-eight thousand, two hundred fifty-seven".