1221011000 has 96 divisors (see below), whose sum is σ = 3140832240. Its totient is φ = 443960000.

The previous prime is 1221010997. The next prime is 1221011021. The reversal of 1221011000 is 1101221.

It is a Harshad number since it is a multiple of its sum of digits (8).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 115955 + ... + 126045.

Almost surely, 2^1221011000 is an apocalyptic number.

1221011000 is a gapful number since it is divisible by the number (10) 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 1221011000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1570416120).

1221011000 is an abundant number, since it is smaller than the sum of its proper divisors (1919821240).

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

1221011000 is a wasteful number, since it uses less digits than its factorization.

1221011000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10134 (or 10109 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 8.

The square root of 1221011000 is about 34942.9678190047. The cubic root of 1221011000 is about 1068.8248080965.

Adding to 1221011000 its reverse (1101221), we get a palindrome (1222112221).

It can be divided in two parts, 12 and 21011000, that added together give a palindrome (21011012).

The spelling of 1221011000 in words is "one billion, two hundred twenty-one million, eleven thousand".