21098389 has 4 divisors (see below), whose sum is σ = 22721356. Its totient is φ = 19475424.

The previous prime is 21098381. The next prime is 21098401. The reversal of 21098389 is 98389012.

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 12659364 + 8439025 = 3558^2 + 2905^2 .

It is a cyclic number.

It is not a de Polignac number, because 21098389 - 2³ = 21098381 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21098381) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 811464 + ... + 811489.

It is an arithmetic number, because the mean of its divisors is an integer number (5680339).

Almost surely, 2^21098389 is an apocalyptic number.

It is an amenable number.

21098389 is a deficient number, since it is larger than the sum of its proper divisors (1622967).

21098389 is a wasteful number, since it uses less digits than its factorization.

21098389 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1622966.

The product of its (nonzero) digits is 31104, while the sum is 40.

The square root of 21098389 is about 4593.2982703064. The cubic root of 21098389 is about 276.3226159914.

The spelling of 21098389 in words is "twenty-one million, ninety-eight thousand, three hundred eighty-nine".