21021220121210 has 16 divisors (see below), whose sum is σ = 38034249051816. Its totient is φ = 8364920752128.

The previous prime is 21021220121147. The next prime is 21021220121219. The reversal of 21021220121210 is 1212102212012.

It can be written as a sum of positive squares in 4 ways, for example, as 9083635404649 + 11937584716561 = 3013907^2 + 3455081^2 .

It is not an unprimeable number, because it can be changed into a prime (21021220121219) 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, 5445910019 + ... + 5445913878.

Almost surely, 2^{21021220121210} is an apocalyptic number.

21021220121210 is a deficient number, since it is larger than the sum of its proper divisors (17013028930606).

21021220121210 is a wasteful number, since it uses less digits than its factorization.

21021220121210 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10891824097.

The product of its (nonzero) digits is 64, while the sum is 17.

Adding to 21021220121210 its reverse (1212102212012), we get a palindrome (22233322333222).

The spelling of 21021220121210 in words is "twenty-one trillion, twenty-one billion, two hundred twenty million, one hundred twenty-one thousand, two hundred ten".