801821621 has 2 divisors, whose sum is σ = 801821622. Its totient is φ = 801821620.

The previous prime is 801821599. The next prime is 801821659. The reversal of 801821621 is 126128108.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 428945521 + 372876100 = 20711^2 + 19310^2 .

It is a cyclic number.

It is not a de Polignac number, because 801821621 - 2¹⁰ = 801820597 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (801821221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 400910810 + 400910811.

It is an arithmetic number, because the mean of its divisors is an integer number (400910811).

Almost surely, 2^801821621 is an apocalyptic number.

It is an amenable number.

801821621 is a deficient number, since it is larger than the sum of its proper divisors (1).

801821621 is an equidigital number, since it uses as much as digits as its factorization.

801821621 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1536, while the sum is 29.

The square root of 801821621 is about 28316.4549511410. The cubic root of 801821621 is about 929.0218339072.

Adding to 801821621 its reverse (126128108), we get a palindrome (927949729).

The spelling of 801821621 in words is "eight hundred one million, eight hundred twenty-one thousand, six hundred twenty-one".