21005269 has 2 divisors, whose sum is σ = 21005270. Its totient is φ = 21005268.

The previous prime is 21005227. The next prime is 21005291. The reversal of 21005269 is 96250012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14730244 + 6275025 = 3838^2 + 2505^2 .

It is a cyclic number.

It is not a de Polignac number, because 21005269 - 2²¹ = 18908117 is a prime.

It is a super-2 number, since 2×21005269² = 882442651524722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21005209) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10502634 + 10502635.

It is an arithmetic number, because the mean of its divisors is an integer number (10502635).

Almost surely, 2^21005269 is an apocalyptic number.

It is an amenable number.

21005269 is a deficient number, since it is larger than the sum of its proper divisors (1).

21005269 is an equidigital number, since it uses as much as digits as its factorization.

21005269 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1080, while the sum is 25.

The square root of 21005269 is about 4583.1505539312. The cubic root of 21005269 is about 275.9154899490.

The spelling of 21005269 in words is "twenty-one million, five thousand, two hundred sixty-nine".