645929551 has 2 divisors, whose sum is σ = 645929552. Its totient is φ = 645929550.

The previous prime is 645929527. The next prime is 645929579. The reversal of 645929551 is 155929546.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 645929551 - 2⁵ = 645929519 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (645929521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322964775 + 322964776.

It is an arithmetic number, because the mean of its divisors is an integer number (322964776).

Almost surely, 2^645929551 is an apocalyptic number.

645929551 is a deficient number, since it is larger than the sum of its proper divisors (1).

645929551 is an equidigital number, since it uses as much as digits as its factorization.

645929551 is an evil number, because the sum of its binary digits is even.

The product of its digits is 486000, while the sum is 46.

The square root of 645929551 is about 25415.1441270751. The cubic root of 645929551 is about 864.4271217599.

The spelling of 645929551 in words is "six hundred forty-five million, nine hundred twenty-nine thousand, five hundred fifty-one".