211221100021 has 8 divisors (see below), whose sum is σ = 211361377304. Its totient is φ = 211080867840.

The previous prime is 211221099989. The next prime is 211221100031. The reversal of 211221100021 is 120001122112.

It can be written as a sum of positive squares in 4 ways, for example, as 42472675921 + 168748424100 = 206089^2 + 410790^2 .

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 211221100021 - 2⁵ = 211221099989 is a prime.

It is a super-2 number, since 2×211221100021² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 211221099974 and 211221100010.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (211221100031) 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, 16200121 + ... + 16213153.

It is an arithmetic number, because the mean of its divisors is an integer number (26420172163).

Almost surely, 2^211221100021 is an apocalyptic number.

It is an amenable number.

211221100021 is a deficient number, since it is larger than the sum of its proper divisors (140277283).

211221100021 is a wasteful number, since it uses less digits than its factorization.

211221100021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22551.

The product of its (nonzero) digits is 16, while the sum is 13.

Adding to 211221100021 its reverse (120001122112), we get a palindrome (331222222133).

The spelling of 211221100021 in words is "two hundred eleven billion, two hundred twenty-one million, one hundred thousand, twenty-one".