1643449651 has 2 divisors, whose sum is σ = 1643449652. Its totient is φ = 1643449650.

The previous prime is 1643449607. The next prime is 1643449663. The reversal of 1643449651 is 1569443461.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1643449651 - 2¹⁵ = 1643416883 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1643449598 and 1643449607.

It is not a weakly prime, because it can be changed into another prime (1643449051) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 821724825 + 821724826.

It is an arithmetic number, because the mean of its divisors is an integer number (821724826).

Almost surely, 2^1643449651 is an apocalyptic number.

1643449651 is a deficient number, since it is larger than the sum of its proper divisors (1).

1643449651 is an equidigital number, since it uses as much as digits as its factorization.

1643449651 is an evil number, because the sum of its binary digits is even.

The product of its digits is 311040, while the sum is 43.

The square root of 1643449651 is about 40539.4826188002. The cubic root of 1643449651 is about 1180.0999750112.

The spelling of 1643449651 in words is "one billion, six hundred forty-three million, four hundred forty-nine thousand, six hundred fifty-one".