21869845 has 4 divisors (see below), whose sum is σ = 26243820. Its totient is φ = 17495872.

The previous prime is 21869839. The next prime is 21869879. The reversal of 21869845 is 54896812.

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 10640644 + 11229201 = 3262^2 + 3351^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21869845 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2186980 + ... + 2186989.

It is an arithmetic number, because the mean of its divisors is an integer number (6560955).

Almost surely, 2^21869845 is an apocalyptic number.

It is an amenable number.

21869845 is a deficient number, since it is larger than the sum of its proper divisors (4373975).

21869845 is an equidigital number, since it uses as much as digits as its factorization.

21869845 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4373974.

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

The square root of 21869845 is about 4676.5206083155. The cubic root of 21869845 is about 279.6502648744.

The spelling of 21869845 in words is "twenty-one million, eight hundred sixty-nine thousand, eight hundred forty-five".