20101212221 has 4 divisors (see below), whose sum is σ = 20794357500. Its totient is φ = 19408066944.

The previous prime is 20101212211. The next prime is 20101212223. The reversal of 20101212221 is 12221210102.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 15637502500 + 4463709721 = 125050^2 + 66811^2 .

It is a cyclic number.

It is not a de Polignac number, because 20101212221 - 2²² = 20097017917 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20101212196 and 20101212205.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20101212223) 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, 346572596 + ... + 346572653.

It is an arithmetic number, because the mean of its divisors is an integer number (5198589375).

Almost surely, 2^20101212221 is an apocalyptic number.

It is an amenable number.

20101212221 is a deficient number, since it is larger than the sum of its proper divisors (693145279).

20101212221 is an equidigital number, since it uses as much as digits as its factorization.

20101212221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 693145278.

The product of its (nonzero) digits is 32, while the sum is 14.

Adding to 20101212221 its reverse (12221210102), we get a palindrome (32322422323).

The spelling of 20101212221 in words is "twenty billion, one hundred one million, two hundred twelve thousand, two hundred twenty-one".