21828493 has 8 divisors (see below), whose sum is σ = 23235768. Its totient is φ = 20434944.

The previous prime is 21828491. The next prime is 21828497. The reversal of 21828493 is 39482812.

It can be written as a sum of positive squares in 4 ways, for example, as 178084 + 21650409 = 422^2 + 4653^2 .

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 21828493 - 2¹ = 21828491 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21828491) 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, 46 + ... + 6607.

It is an arithmetic number, because the mean of its divisors is an integer number (2904471).

Almost surely, 2^21828493 is an apocalyptic number.

It is an amenable number.

21828493 is a deficient number, since it is larger than the sum of its proper divisors (1407275).

21828493 is a wasteful number, since it uses less digits than its factorization.

21828493 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6863.

The product of its digits is 27648, while the sum is 37.

The square root of 21828493 is about 4672.0972806653. The cubic root of 21828493 is about 279.4738973088.

The spelling of 21828493 in words is "twenty-one million, eight hundred twenty-eight thousand, four hundred ninety-three".