821238220877 has 2 divisors, whose sum is σ = 821238220878. Its totient is φ = 821238220876.

The previous prime is 821238220849. The next prime is 821238220919. The reversal of 821238220877 is 778022832128.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 433919943076 + 387318277801 = 658726^2 + 622349^2 .

It is a cyclic number.

It is not a de Polignac number, because 821238220877 - 2¹⁶ = 821238155341 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (821238223877) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 410619110438 + 410619110439.

It is an arithmetic number, because the mean of its divisors is an integer number (410619110439).

Almost surely, 2^821238220877 is an apocalyptic number.

It is an amenable number.

821238220877 is a deficient number, since it is larger than the sum of its proper divisors (1).

821238220877 is an equidigital number, since it uses as much as digits as its factorization.

821238220877 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1204224, while the sum is 50.

The spelling of 821238220877 in words is "eight hundred twenty-one billion, two hundred thirty-eight million, two hundred twenty thousand, eight hundred seventy-seven".