821381633 has 2 divisors, whose sum is σ = 821381634. Its totient is φ = 821381632.

The previous prime is 821381629. The next prime is 821381641. The reversal of 821381633 is 336183128.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 494929009 + 326452624 = 22247^2 + 18068^2 .

It is a cyclic number.

It is not a de Polignac number, because 821381633 - 2² = 821381629 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 821381593 and 821381602.

It is not a weakly prime, because it can be changed into another prime (821381663) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 410690816 + 410690817.

It is an arithmetic number, because the mean of its divisors is an integer number (410690817).

Almost surely, 2^821381633 is an apocalyptic number.

It is an amenable number.

821381633 is a deficient number, since it is larger than the sum of its proper divisors (1).

821381633 is an equidigital number, since it uses as much as digits as its factorization.

821381633 is an evil number, because the sum of its binary digits is even.

The product of its digits is 20736, while the sum is 35.

The square root of 821381633 is about 28659.7563318323. The cubic root of 821381633 is about 936.5155563246.

The spelling of 821381633 in words is "eight hundred twenty-one million, three hundred eighty-one thousand, six hundred thirty-three".