21213101 has 16 divisors (see below), whose sum is σ = 27484800. Its totient is φ = 15899328.

The previous prime is 21213097. The next prime is 21213109. The reversal of 21213101 is 10131212.

It is a cyclic number.

It is not a de Polignac number, because 21213101 - 2² = 21213097 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21213109) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4406 + ... + 7863.

It is an arithmetic number, because the mean of its divisors is an integer number (1717800).

Almost surely, 2^21213101 is an apocalyptic number.

It is an amenable number.

21213101 is a deficient number, since it is larger than the sum of its proper divisors (6271699).

21213101 is a wasteful number, since it uses less digits than its factorization.

21213101 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12308.

The product of its (nonzero) digits is 12, while the sum is 11.

The square root of 21213101 is about 4605.7682312509. The cubic root of 21213101 is about 276.8225000713.

Adding to 21213101 its reverse (10131212), we get a palindrome (31344313).

The spelling of 21213101 in words is "twenty-one million, two hundred thirteen thousand, one hundred one".