21221101000 has 192 divisors, whose sum is σ = 55117062000. Its totient is φ = 7641216000.

The previous prime is 21221100997. The next prime is 21221101019. The reversal of 21221101000 is 10112212.

It can be written as a sum of positive squares in 8 ways, for example, as 6744679876 + 14476421124 = 82126^2 + 120318^2 .

It is a Harshad number since it is a multiple of its sum of digits (10).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 13188196 + ... + 13189804.

Almost surely, 2^21221101000 is an apocalyptic number.

21221101000 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21221101000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27558531000).

21221101000 is an abundant number, since it is smaller than the sum of its proper divisors (33895961000).

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

21221101000 is a wasteful number, since it uses less digits than its factorization.

21221101000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1761 (or 1736 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 10.

Adding to 21221101000 its reverse (10112212), we get a palindrome (21231213212).

It can be divided in two parts, 21221 and 101000, that added together give a palindrome (122221).

The spelling of 21221101000 in words is "twenty-one billion, two hundred twenty-one million, one hundred one thousand".