100009821 has 4 divisors (see below), whose sum is σ = 133346432. Its totient is φ = 66673212.

The previous prime is 100009817. The next prime is 100009823. The reversal of 100009821 is 128900001.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 100009821 - 2² = 100009817 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 (100009823) 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, 16668301 + ... + 16668306.

It is an arithmetic number, because the mean of its divisors is an integer number (33336608).

Almost surely, 2^100009821 is an apocalyptic number.

It is an amenable number.

100009821 is a deficient number, since it is larger than the sum of its proper divisors (33336611).

100009821 is an equidigital number, since it uses as much as digits as its factorization.

100009821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33336610.

The product of its (nonzero) digits is 144, while the sum is 21.

The square root of 100009821 is about 10000.4910379441. The cubic root of 100009821 is about 464.1740778785.

Adding to 100009821 its reverse (128900001), we get a palindrome (228909822).

The spelling of 100009821 in words is "one hundred million, nine thousand, eight hundred twenty-one".