1009121821 has 2 divisors, whose sum is σ = 1009121822. Its totient is φ = 1009121820.

The previous prime is 1009121809. The next prime is 1009121843. The reversal of 1009121821 is 1281219001.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 914760025 + 94361796 = 30245^2 + 9714^2 .

It is a cyclic number.

It is not a de Polignac number, because 1009121821 - 2¹³ = 1009113629 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1009121881) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 504560910 + 504560911.

It is an arithmetic number, because the mean of its divisors is an integer number (504560911).

Almost surely, 2^1009121821 is an apocalyptic number.

1009121821 is the 18341-st hex number.

It is an amenable number.

1009121821 is a deficient number, since it is larger than the sum of its proper divisors (1).

1009121821 is an equidigital number, since it uses as much as digits as its factorization.

1009121821 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 288, while the sum is 25.

The square root of 1009121821 is about 31766.6778401519. The cubic root of 1009121821 is about 1003.0314082782.

The spelling of 1009121821 in words is "one billion, nine million, one hundred twenty-one thousand, eight hundred twenty-one".