21101001 has 8 divisors (see below), whose sum is σ = 29615520. Its totient is φ = 13326912.

The previous prime is 21100999. The next prime is 21101027. The reversal of 21101001 is 10010112.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21101001 - 2¹ = 21100999 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21101401) 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 7 ways as a sum of consecutive naturals, for example, 185040 + ... + 185153.

It is an arithmetic number, because the mean of its divisors is an integer number (3701940).

Almost surely, 2^21101001 is an apocalyptic number.

It is an amenable number.

21101001 is a deficient number, since it is larger than the sum of its proper divisors (8514519).

21101001 is a wasteful number, since it uses less digits than its factorization.

21101001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 370215.

The product of its (nonzero) digits is 2, while the sum is 6.

The square root of 21101001 is about 4593.5825887862. The cubic root of 21101001 is about 276.3340185191.

Adding to 21101001 its reverse (10010112), we get a palindrome (31111113).

Multiplying 21101001 by its reverse (10010112), we get a palindrome (211223383322112).

The spelling of 21101001 in words is "twenty-one million, one hundred one thousand, one".