645053551 has 2 divisors, whose sum is σ = 645053552. Its totient is φ = 645053550.

The previous prime is 645053543. The next prime is 645053567. The reversal of 645053551 is 155350546.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 645053551 - 2³ = 645053543 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (645053251) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322526775 + 322526776.

It is an arithmetic number, because the mean of its divisors is an integer number (322526776).

Almost surely, 2^645053551 is an apocalyptic number.

645053551 is a deficient number, since it is larger than the sum of its proper divisors (1).

645053551 is an equidigital number, since it uses as much as digits as its factorization.

645053551 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 45000, while the sum is 34.

The square root of 645053551 is about 25397.9044608015. The cubic root of 645053551 is about 864.0361705929.

The spelling of 645053551 in words is "six hundred forty-five million, fifty-three thousand, five hundred fifty-one".