21019069 has 2 divisors, whose sum is σ = 21019070. Its totient is φ = 21019068.

The previous prime is 21019067. The next prime is 21019127. The reversal of 21019069 is 96091012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18576100 + 2442969 = 4310^2 + 1563^2 .

It is a cyclic number.

It is not a de Polignac number, because 21019069 - 2¹ = 21019067 is a prime.

It is a super-2 number, since 2×21019069² = 883602523253522, which contains 22 as substring.

Together with 21019067, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21019067) 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, 10509534 + 10509535.

It is an arithmetic number, because the mean of its divisors is an integer number (10509535).

Almost surely, 2^21019069 is an apocalyptic number.

It is an amenable number.

21019069 is a deficient number, since it is larger than the sum of its proper divisors (1).

21019069 is an equidigital number, since it uses as much as digits as its factorization.

21019069 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 972, while the sum is 28.

The square root of 21019069 is about 4584.6558213240. The cubic root of 21019069 is about 275.9759001921.

The spelling of 21019069 in words is "twenty-one million, nineteen thousand, sixty-nine".