21244687 has 6 divisors (see below), whose sum is σ = 21464448. Its totient is φ = 21025872.

The previous prime is 21244681. The next prime is 21244693. The reversal of 21244687 is 78644212.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21244681) and next prime (21244693).

It is not a de Polignac number, because 21244687 - 2²³ = 12856079 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21244681) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 51739 + ... + 52147.

It is an arithmetic number, because the mean of its divisors is an integer number (3577408).

Almost surely, 2^21244687 is an apocalyptic number.

21244687 is a deficient number, since it is larger than the sum of its proper divisors (219761).

21244687 is an frugal number, since it uses more digits than its factorization.

21244687 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 945 (or 536 counting only the distinct ones).

The product of its digits is 21504, while the sum is 34.

The square root of 21244687 is about 4609.1959168601. The cubic root of 21244687 is about 276.9598268318.

Adding to 21244687 its reverse (78644212), we get a palindrome (99888899).

The spelling of 21244687 in words is "twenty-one million, two hundred forty-four thousand, six hundred eighty-seven".