21000121222210 has 32 divisors (see below), whose sum is σ = 40770267315120. Its totient is φ = 7742016622848.

The previous prime is 21000121222109. The next prime is 21000121222211. The reversal of 21000121222210 is 1222212100012.

It is a happy number.

It can be written as a sum of positive squares in 8 ways, for example, as 43602868969 + 20956518353241 = 208813^2 + 4577829^2 .

It is not an unprimeable number, because it can be changed into a prime (21000121222211) 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, 123605305 + ... + 123775084.

Almost surely, 2^{21000121222210} is an apocalyptic number.

21000121222210 is a deficient number, since it is larger than the sum of its proper divisors (19770146092910).

21000121222210 is a wasteful number, since it uses less digits than its factorization.

21000121222210 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 247381062.

The product of its (nonzero) digits is 64, while the sum is 16.

Adding to 21000121222210 its reverse (1222212100012), we get a palindrome (22222333322222).

The spelling of 21000121222210 in words is "twenty-one trillion, one hundred twenty-one million, two hundred twenty-two thousand, two hundred ten".