821228647651 has 2 divisors, whose sum is σ = 821228647652. Its totient is φ = 821228647650.

The previous prime is 821228647643. The next prime is 821228647711. The reversal of 821228647651 is 156746822128.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 821228647651 - 2³ = 821228647643 is a prime.

It is not a weakly prime, because it can be changed into another prime (821228644651) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 410614323825 + 410614323826.

It is an arithmetic number, because the mean of its divisors is an integer number (410614323826).

Almost surely, 2^821228647651 is an apocalyptic number.

821228647651 is a deficient number, since it is larger than the sum of its proper divisors (1).

821228647651 is an equidigital number, since it uses as much as digits as its factorization.

821228647651 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2580480, while the sum is 52.

The spelling of 821228647651 in words is "eight hundred twenty-one billion, two hundred twenty-eight million, six hundred forty-seven thousand, six hundred fifty-one".