21100321 has 8 divisors (see below), whose sum is σ = 23508864. Its totient is φ = 18773520.

The previous prime is 21100319. The next prime is 21100351. The reversal of 21100321 is 12300112.

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 21100321 - 2¹ = 21100319 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21100298 and 21100307.

It is not an unprimeable number, because it can be changed into a prime (21100351) 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, 19890 + ... + 20923.

It is an arithmetic number, because the mean of its divisors is an integer number (2938608).

Almost surely, 2^21100321 is an apocalyptic number.

It is an amenable number.

21100321 is a deficient number, since it is larger than the sum of its proper divisors (2408543).

21100321 is a wasteful number, since it uses less digits than its factorization.

21100321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40871.

The product of its (nonzero) digits is 12, while the sum is 10.

The square root of 21100321 is about 4593.5085718871. The cubic root of 21100321 is about 276.3310501109.

Adding to 21100321 its reverse (12300112), we get a palindrome (33400433).

The spelling of 21100321 in words is "twenty-one million, one hundred thousand, three hundred twenty-one".