21185444 has 18 divisors (see below), whose sum is σ = 43127910. Its totient is φ = 9079392.

The previous prime is 21185441. The next prime is 21185447. The reversal of 21185444 is 44458112.

It is an interprime number because it is at equal distance from previous prime (21185441) and next prime (21185447).

It can be written as a sum of positive squares in only one way, i.e., 18593344 + 2592100 = 4312^2 + 1610^2 .

It is not an unprimeable number, because it can be changed into a prime (21185441) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 53849 + ... + 54240.

It is an arithmetic number, because the mean of its divisors is an integer number (2395995).

Almost surely, 2^21185444 is an apocalyptic number.

It is an amenable number.

21185444 is an abundant number, since it is smaller than the sum of its proper divisors (21942466).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21185444 is a wasteful number, since it uses less digits than its factorization.

21185444 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 108107 (or 108098 counting only the distinct ones).

The product of its digits is 5120, while the sum is 29.

The square root of 21185444 is about 4602.7648212786. The cubic root of 21185444 is about 276.7021434805.

The spelling of 21185444 in words is "twenty-one million, one hundred eighty-five thousand, four hundred forty-four".