21485869 has 4 divisors (see below), whose sum is σ = 21504796. Its totient is φ = 21466944.

The previous prime is 21485857. The next prime is 21485879. The reversal of 21485869 is 96858412.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 10176100 + 11309769 = 3190^2 + 3363^2 .

It is a cyclic number.

It is not a de Polignac number, because 21485869 - 2⁷ = 21485741 is a prime.

It is a super-2 number, since 2×21485869² = 923285133370322, 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 (21485809) 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, 7644 + ... + 10069.

It is an arithmetic number, because the mean of its divisors is an integer number (5376199).

Almost surely, 2^21485869 is an apocalyptic number.

It is an amenable number.

21485869 is a deficient number, since it is larger than the sum of its proper divisors (18927).

21485869 is a wasteful number, since it uses less digits than its factorization.

21485869 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18926.

The product of its digits is 138240, while the sum is 43.

The square root of 21485869 is about 4635.2852123683. The cubic root of 21485869 is about 278.0039550530.

The spelling of 21485869 in words is "twenty-one million, four hundred eighty-five thousand, eight hundred sixty-nine".