21873449 has 4 divisors (see below), whose sum is σ = 23556036. Its totient is φ = 20190864.

The previous prime is 21873433. The next prime is 21873451. The reversal of 21873449 is 94437812.

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 10530025 + 11343424 = 3245^2 + 3368^2 .

It is a cyclic number.

It is not a de Polignac number, because 21873449 - 2⁴ = 21873433 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21873409) 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, 841274 + ... + 841299.

It is an arithmetic number, because the mean of its divisors is an integer number (5889009).

Almost surely, 2^21873449 is an apocalyptic number.

It is an amenable number.

21873449 is a deficient number, since it is larger than the sum of its proper divisors (1682587).

21873449 is a wasteful number, since it uses less digits than its factorization.

21873449 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1682586.

The product of its digits is 48384, while the sum is 38.

The square root of 21873449 is about 4676.9059216538. The cubic root of 21873449 is about 279.6656255106.

It can be divided in two parts, 21873 and 449, that added together give a palindrome (22322).

The spelling of 21873449 in words is "twenty-one million, eight hundred seventy-three thousand, four hundred forty-nine".