21565469 has 12 divisors (see below), whose sum is σ = 23253408. Its totient is φ = 19992000.

The previous prime is 21565463. The next prime is 21565471. The reversal of 21565469 is 96456512.

It is a de Polignac number, because none of the positive numbers 2^k-21565469 is a prime.

It is a super-2 number, since 2×21565469² = 930138906379922, 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 (21565463) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 19994 + ... + 21044.

It is an arithmetic number, because the mean of its divisors is an integer number (1937784).

Almost surely, 2^21565469 is an apocalyptic number.

It is an amenable number.

21565469 is a deficient number, since it is larger than the sum of its proper divisors (1687939).

21565469 is a wasteful number, since it uses less digits than its factorization.

21565469 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1156 (or 1139 counting only the distinct ones).

The product of its digits is 64800, while the sum is 38.

The square root of 21565469 is about 4643.8635854211. The cubic root of 21565469 is about 278.3468446555.

The spelling of 21565469 in words is "twenty-one million, five hundred sixty-five thousand, four hundred sixty-nine".