21244557 has 8 divisors (see below), whose sum is σ = 28395360. Its totient is φ = 14128400.

The previous prime is 21244507. The next prime is 21244583. The reversal of 21244557 is 75544212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21244557 - 2¹⁰ = 21243533 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21244507) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7194 + ... + 9707.

It is an arithmetic number, because the mean of its divisors is an integer number (3549420).

Almost surely, 2^21244557 is an apocalyptic number.

It is an amenable number.

21244557 is a deficient number, since it is larger than the sum of its proper divisors (7150803).

21244557 is a wasteful number, since it uses less digits than its factorization.

21244557 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17323.

The product of its digits is 11200, while the sum is 30.

The square root of 21244557 is about 4609.1818145957. The cubic root of 21244557 is about 276.9592619086.

Adding to 21244557 its reverse (75544212), we get a palindrome (96788769).

The spelling of 21244557 in words is "twenty-one million, two hundred forty-four thousand, five hundred fifty-seven".