21111211000 has 128 divisors (see below), whose sum is σ = 54652216320. Its totient is φ = 7568400000.

The previous prime is 21111210977. The next prime is 21111211003. The reversal of 21111211000 is 11211112.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21111211003) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 767485 + ... + 794515.

It is an arithmetic number, because the mean of its divisors is an integer number (426970440).

Almost surely, 2^21111211000 is an apocalyptic number.

21111211000 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 21111211000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27326108160).

21111211000 is an abundant number, since it is smaller than the sum of its proper divisors (33541005320).

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

21111211000 is a wasteful number, since it uses less digits than its factorization.

21111211000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27134 (or 27120 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 10.

Adding to 21111211000 its reverse (11211112), we get a palindrome (21122422112).

It can be divided in two parts, 211 and 11211000, that added together give a palindrome (11211211).

The spelling of 21111211000 in words is "twenty-one billion, one hundred eleven million, two hundred eleven thousand".