645223091 has 2 divisors, whose sum is σ = 645223092. Its totient is φ = 645223090.

The previous prime is 645223081. The next prime is 645223121. The reversal of 645223091 is 190322546.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-645223091 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (645223081) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322611545 + 322611546.

It is an arithmetic number, because the mean of its divisors is an integer number (322611546).

Almost surely, 2^645223091 is an apocalyptic number.

645223091 is a deficient number, since it is larger than the sum of its proper divisors (1).

645223091 is an equidigital number, since it uses as much as digits as its factorization.

645223091 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 12960, while the sum is 32.

The square root of 645223091 is about 25401.2419184575. The cubic root of 645223091 is about 864.1118624277. Note that the first 3 decimals are identical.

The spelling of 645223091 in words is "six hundred forty-five million, two hundred twenty-three thousand, ninety-one".