21505069 has 4 divisors (see below), whose sum is σ = 22440096. Its totient is φ = 20570044.

The previous prime is 21505063. The next prime is 21505109. The reversal of 21505069 is 96050512.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21505069 - 2⁹ = 21504557 is a prime.

It is a super-2 number, since 2×21505069² = 924935985389522, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21505063) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 467479 + ... + 467524.

It is an arithmetic number, because the mean of its divisors is an integer number (5610024).

Almost surely, 2^21505069 is an apocalyptic number.

It is an amenable number.

21505069 is a deficient number, since it is larger than the sum of its proper divisors (935027).

21505069 is an equidigital number, since it uses as much as digits as its factorization.

21505069 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 935026.

The product of its (nonzero) digits is 2700, while the sum is 28.

The square root of 21505069 is about 4637.3558198611. The cubic root of 21505069 is about 278.0867394914.

The spelling of 21505069 in words is "twenty-one million, five hundred five thousand, sixty-nine".