645557041 has 2 divisors, whose sum is σ = 645557042. Its totient is φ = 645557040.

The previous prime is 645557021. The next prime is 645557089. The reversal of 645557041 is 140755546.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 524226816 + 121330225 = 22896^2 + 11015^2 .

It is a cyclic number.

It is not a de Polignac number, because 645557041 - 2⁹ = 645556529 is a prime.

It is not a weakly prime, because it can be changed into another prime (645557021) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322778520 + 322778521.

It is an arithmetic number, because the mean of its divisors is an integer number (322778521).

Almost surely, 2^645557041 is an apocalyptic number.

It is an amenable number.

645557041 is a deficient number, since it is larger than the sum of its proper divisors (1).

645557041 is an equidigital number, since it uses as much as digits as its factorization.

645557041 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 84000, while the sum is 37.

The square root of 645557041 is about 25407.8145656017. The cubic root of 645557041 is about 864.2609170153.

The spelling of 645557041 in words is "six hundred forty-five million, five hundred fifty-seven thousand, forty-one".