649971643 has 2 divisors, whose sum is σ = 649971644. Its totient is φ = 649971642.

The previous prime is 649971629. The next prime is 649971661. The reversal of 649971643 is 346179946.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 649971643 - 2²⁵ = 616417211 is a prime.

It is not a weakly prime, because it can be changed into another prime (649971613) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 324985821 + 324985822.

It is an arithmetic number, because the mean of its divisors is an integer number (324985822).

Almost surely, 2^649971643 is an apocalyptic number.

649971643 is a deficient number, since it is larger than the sum of its proper divisors (1).

649971643 is an equidigital number, since it uses as much as digits as its factorization.

649971643 is an evil number, because the sum of its binary digits is even.

The product of its digits is 979776, while the sum is 49.

The square root of 649971643 is about 25494.5414353740. The cubic root of 649971643 is about 866.2265082642.

The spelling of 649971643 in words is "six hundred forty-nine million, nine hundred seventy-one thousand, six hundred forty-three".