21001211221000 has 64 divisors (see below), whose sum is σ = 49207412694960. Its totient is φ = 8389445440000.

The previous prime is 21001211220991. The next prime is 21001211221009. The reversal of 21001211221000 is 12211210012.

It is an interprime number because it is at equal distance from previous prime (21001211220991) and next prime (21001211221009).

It can be written as a sum of positive squares in 8 ways, for example, as 3694230073444 + 17306981147556 = 1922038^2 + 4160166^2 .

It is not an unprimeable number, because it can be changed into a prime (21001211221009) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13037431 + ... + 14559430.

Almost surely, 2^{21001211221000} is an apocalyptic number.

21001211221000 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21001211221000 is an abundant number, since it is smaller than the sum of its proper divisors (28206201473960).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21001211221000 is a wasteful number, since it uses less digits than its factorization.

21001211221000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27597643 (or 27597629 counting only the distinct ones).

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

Adding to 21001211221000 its reverse (12211210012), we get a palindrome (21013422431012).

The spelling of 21001211221000 in words is "twenty-one trillion, one billion, two hundred eleven million, two hundred twenty-one thousand".