11801821 has 2 divisors, whose sum is σ = 11801822. Its totient is φ = 11801820.

The previous prime is 11801771. The next prime is 11801827. The reversal of 11801821 is 12810811.

11801821 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 10150596 + 1651225 = 3186^2 + 1285^2 .

It is a cyclic number.

It is not a de Polignac number, because 11801821 - 2⁷ = 11801693 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 11801792 and 11801801.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (11801827) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5900910 + 5900911.

It is an arithmetic number, because the mean of its divisors is an integer number (5900911).

Almost surely, 2^11801821 is an apocalyptic number.

It is an amenable number.

11801821 is a deficient number, since it is larger than the sum of its proper divisors (1).

11801821 is an equidigital number, since it uses as much as digits as its factorization.

11801821 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 128, while the sum is 22.

The square root of 11801821 is about 3435.3778540359. The cubic root of 11801821 is about 227.6755220747.

The spelling of 11801821 in words is "eleven million, eight hundred one thousand, eight hundred twenty-one".