645813061 has 2 divisors, whose sum is σ = 645813062. Its totient is φ = 645813060.

The previous prime is 645813053. The next prime is 645813073. The reversal of 645813061 is 160318546.

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., 452880961 + 192932100 = 21281^2 + 13890^2 .

It is a cyclic number.

It is not a de Polignac number, because 645813061 - 2³ = 645813053 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (645813011) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322906530 + 322906531.

It is an arithmetic number, because the mean of its divisors is an integer number (322906531).

Almost surely, 2^645813061 is an apocalyptic number.

It is an amenable number.

645813061 is a deficient number, since it is larger than the sum of its proper divisors (1).

645813061 is an equidigital number, since it uses as much as digits as its factorization.

645813061 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 17280, while the sum is 34.

The square root of 645813061 is about 25412.8522798996. The cubic root of 645813061 is about 864.3751536728.

The spelling of 645813061 in words is "six hundred forty-five million, eight hundred thirteen thousand, sixty-one".