21361091 has 2 divisors, whose sum is σ = 21361092. Its totient is φ = 21361090.

The previous prime is 21361079. The next prime is 21361097. The reversal of 21361091 is 19016312.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21361091 is a prime.

It is not a weakly prime, because it can be changed into another prime (21361097) 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, 10680545 + 10680546.

It is an arithmetic number, because the mean of its divisors is an integer number (10680546).

Almost surely, 2^21361091 is an apocalyptic number.

21361091 is a deficient number, since it is larger than the sum of its proper divisors (1).

21361091 is an equidigital number, since it uses as much as digits as its factorization.

21361091 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 324, while the sum is 23.

The square root of 21361091 is about 4621.8060322779. The cubic root of 21361091 is about 277.4647456769.

The spelling of 21361091 in words is "twenty-one million, three hundred sixty-one thousand, ninety-one".