21098181 has 16 divisors (see below), whose sum is σ = 30462656. Its totient is φ = 12911616.

The previous prime is 21098171. The next prime is 21098183. The reversal of 21098181 is 18189012.

It is not a de Polignac number, because 21098181 - 2⁷ = 21098053 is a prime.

It is a super-2 number, since 2×21098181² = 890266483017522, which contains 22 as substring.

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 (21098183) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6126 + ... + 8928.

It is an arithmetic number, because the mean of its divisors is an integer number (1903916).

Almost surely, 2^21098181 is an apocalyptic number.

It is an amenable number.

21098181 is a deficient number, since it is larger than the sum of its proper divisors (9364475).

21098181 is a wasteful number, since it uses less digits than its factorization.

21098181 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3012.

The product of its (nonzero) digits is 1152, while the sum is 30.

The square root of 21098181 is about 4593.2756285684. The cubic root of 21098181 is about 276.3217079396.

The spelling of 21098181 in words is "twenty-one million, ninety-eight thousand, one hundred eighty-one".