1643251457 has 2 divisors, whose sum is σ = 1643251458. Its totient is φ = 1643251456.

The previous prime is 1643251453. The next prime is 1643251469. The reversal of 1643251457 is 7541523461.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1571408881 + 71842576 = 39641^2 + 8476^2 .

It is a cyclic number.

It is not a de Polignac number, because 1643251457 - 2² = 1643251453 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1643251457.

It is not a weakly prime, because it can be changed into another prime (1643251451) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 821625728 + 821625729.

It is an arithmetic number, because the mean of its divisors is an integer number (821625729).

Almost surely, 2^1643251457 is an apocalyptic number.

It is an amenable number.

1643251457 is a deficient number, since it is larger than the sum of its proper divisors (1).

1643251457 is an equidigital number, since it uses as much as digits as its factorization.

1643251457 is an evil number, because the sum of its binary digits is even.

The product of its digits is 100800, while the sum is 38.

The square root of 1643251457 is about 40537.0380886418. The cubic root of 1643251457 is about 1180.0525345279.

The spelling of 1643251457 in words is "one billion, six hundred forty-three million, two hundred fifty-one thousand, four hundred fifty-seven".