21241985 has 4 divisors (see below), whose sum is σ = 25490388. Its totient is φ = 16993584.

The previous prime is 21241973. The next prime is 21241991. The reversal of 21241985 is 58914212.

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 16777216 + 4464769 = 4096^2 + 2113^2 .

It is a cyclic number.

It is not a de Polignac number, because 21241985 - 2⁶ = 21241921 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2124194 + ... + 2124203.

It is an arithmetic number, because the mean of its divisors is an integer number (6372597).

Almost surely, 2^21241985 is an apocalyptic number.

It is an amenable number.

21241985 is a deficient number, since it is larger than the sum of its proper divisors (4248403).

21241985 is an equidigital number, since it uses as much as digits as its factorization.

21241985 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4248402.

The product of its digits is 5760, while the sum is 32.

The square root of 21241985 is about 4608.9027978468. The cubic root of 21241985 is about 276.9480846461.

The spelling of 21241985 in words is "twenty-one million, two hundred forty-one thousand, nine hundred eighty-five".