21098851 has 4 divisors (see below), whose sum is σ = 21109032. Its totient is φ = 21088672.

The previous prime is 21098839. The next prime is 21098867. The reversal of 21098851 is 15889012.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21098851 - 2⁹ = 21098339 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21098881) 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, 745 + ... + 6538.

It is an arithmetic number, because the mean of its divisors is an integer number (5277258).

Almost surely, 2^21098851 is an apocalyptic number.

21098851 is a deficient number, since it is larger than the sum of its proper divisors (10181).

21098851 is an equidigital number, since it uses as much as digits as its factorization.

21098851 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10180.

The product of its (nonzero) digits is 5760, while the sum is 34.

The square root of 21098851 is about 4593.3485606908. The cubic root of 21098851 is about 276.3246328929.

The spelling of 21098851 in words is "twenty-one million, ninety-eight thousand, eight hundred fifty-one".