11891021 has 2 divisors, whose sum is σ = 11891022. Its totient is φ = 11891020.

The previous prime is 11891003. The next prime is 11891053. The reversal of 11891021 is 12019811.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11055625 + 835396 = 3325^2 + 914^2 .

It is a cyclic number.

It is not a de Polignac number, because 11891021 - 2¹⁴ = 11874637 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (11891071) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5945510 + 5945511.

It is an arithmetic number, because the mean of its divisors is an integer number (5945511).

Almost surely, 2^11891021 is an apocalyptic number.

It is an amenable number.

11891021 is a deficient number, since it is larger than the sum of its proper divisors (1).

11891021 is an equidigital number, since it uses as much as digits as its factorization.

11891021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 144, while the sum is 23.

The square root of 11891021 is about 3448.3359755105. The cubic root of 11891021 is about 228.2476853311.

The spelling of 11891021 in words is "eleven million, eight hundred ninety-one thousand, twenty-one".