21243849 has 24 divisors (see below), whose sum is σ = 31881696. Its totient is φ = 12566400.

The previous prime is 21243841. The next prime is 21243857. The reversal of 21243849 is 94834212.

It is an interprime number because it is at equal distance from previous prime (21243841) and next prime (21243857).

It is not a de Polignac number, because 21243849 - 2³ = 21243841 is a prime.

It is a super-2 number, since 2×21243849² = 902602240669602, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is not an unprimeable number, because it can be changed into a prime (21243841) 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 23 ways as a sum of consecutive naturals, for example, 14929 + ... + 16289.

It is an arithmetic number, because the mean of its divisors is an integer number (1328404).

Almost surely, 2^21243849 is an apocalyptic number.

It is an amenable number.

21243849 is a deficient number, since it is larger than the sum of its proper divisors (10637847).

21243849 is a wasteful number, since it uses less digits than its factorization.

21243849 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1429 (or 1418 counting only the distinct ones).

The product of its digits is 13824, while the sum is 33.

The square root of 21243849 is about 4609.1050107369. The cubic root of 21243849 is about 276.9561852093.

The spelling of 21243849 in words is "twenty-one million, two hundred forty-three thousand, eight hundred forty-nine".