21191603 has 2 divisors, whose sum is σ = 21191604. Its totient is φ = 21191602.

The previous prime is 21191591. The next prime is 21191617. The reversal of 21191603 is 30619112.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21191603 - 2⁶ = 21191539 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (21191623) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10595801 + 10595802.

It is an arithmetic number, because the mean of its divisors is an integer number (10595802).

Almost surely, 2^21191603 is an apocalyptic number.

21191603 is a deficient number, since it is larger than the sum of its proper divisors (1).

21191603 is an equidigital number, since it uses as much as digits as its factorization.

21191603 is an evil number, because the sum of its binary digits is even.

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

The square root of 21191603 is about 4603.4338270469. The cubic root of 21191603 is about 276.7289550243.

The spelling of 21191603 in words is "twenty-one million, one hundred ninety-one thousand, six hundred three".