21101221000 has 64 divisors (see below), whose sum is σ = 49399608960. Its totient is φ = 8436600000.

The previous prime is 21101220991. The next prime is 21101221021. The reversal of 21101221000 is 12210112.

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

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3267775 + ... + 3274225.

It is an arithmetic number, because the mean of its divisors is an integer number (771868890).

Almost surely, 2^21101221000 is an apocalyptic number.

21101221000 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21101221000 is an abundant number, since it is smaller than the sum of its proper divisors (28298387960).

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

21101221000 is a wasteful number, since it uses less digits than its factorization.

21101221000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9743 (or 9729 counting only the distinct ones).

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

Adding to 21101221000 its reverse (12210112), we get a palindrome (21113431112).

The spelling of 21101221000 in words is "twenty-one billion, one hundred one million, two hundred twenty-one thousand".