645556099 has 2 divisors, whose sum is σ = 645556100. Its totient is φ = 645556098.

The previous prime is 645556061. The next prime is 645556117. The reversal of 645556099 is 990655546.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 645556099 - 2⁷ = 645555971 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (645556039) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322778049 + 322778050.

It is an arithmetic number, because the mean of its divisors is an integer number (322778050).

Almost surely, 2^645556099 is an apocalyptic number.

645556099 is a deficient number, since it is larger than the sum of its proper divisors (1).

645556099 is an equidigital number, since it uses as much as digits as its factorization.

645556099 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1458000, while the sum is 49.

The square root of 645556099 is about 25407.7960279911. The cubic root of 645556099 is about 864.2604966372.

The spelling of 645556099 in words is "six hundred forty-five million, five hundred fifty-six thousand, ninety-nine".