21019849 has 2 divisors, whose sum is σ = 21019850. Its totient is φ = 21019848.

The previous prime is 21019841. The next prime is 21019879. The reversal of 21019849 is 94891012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18020025 + 2999824 = 4245^2 + 1732^2 .

It is a cyclic number.

It is not a de Polignac number, because 21019849 - 2³ = 21019841 is a prime.

It is not a weakly prime, because it can be changed into another prime (21019841) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10509924 + 10509925.

It is an arithmetic number, because the mean of its divisors is an integer number (10509925).

Almost surely, 2^21019849 is an apocalyptic number.

It is an amenable number.

21019849 is a deficient number, since it is larger than the sum of its proper divisors (1).

21019849 is an equidigital number, since it uses as much as digits as its factorization.

21019849 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5184, while the sum is 34.

The square root of 21019849 is about 4584.7408868986. The cubic root of 21019849 is about 275.9793138946.

The spelling of 21019849 in words is "twenty-one million, nineteen thousand, eight hundred forty-nine".