1645217257 has 2 divisors, whose sum is σ = 1645217258. Its totient is φ = 1645217256.

The previous prime is 1645217251. The next prime is 1645217267. The reversal of 1645217257 is 7527125461.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1626992896 + 18224361 = 40336^2 + 4269^2 .

It is a cyclic number.

It is not a de Polignac number, because 1645217257 - 2⁷ = 1645217129 is a prime.

It is not a weakly prime, because it can be changed into another prime (1645217251) 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, 822608628 + 822608629.

It is an arithmetic number, because the mean of its divisors is an integer number (822608629).

Almost surely, 2^1645217257 is an apocalyptic number.

It is an amenable number.

1645217257 is a deficient number, since it is larger than the sum of its proper divisors (1).

1645217257 is an equidigital number, since it uses as much as digits as its factorization.

1645217257 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 117600, while the sum is 40.

The square root of 1645217257 is about 40561.2778028503. The cubic root of 1645217257 is about 1180.5229074277.

The spelling of 1645217257 in words is "one billion, six hundred forty-five million, two hundred seventeen thousand, two hundred fifty-seven".