1221211000 has 64 divisors (see below), whose sum is σ = 2862812160. Its totient is φ = 487600000.

The previous prime is 1221210989. The next prime is 1221211021. The reversal of 1221211000 is 1121221.

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 15 ways as a sum of consecutive naturals, for example, 1060425 + ... + 1061575.

It is an arithmetic number, because the mean of its divisors is an integer number (44731440).

Almost surely, 2^1221211000 is an apocalyptic number.

1221211000 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 1221211000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1431406080).

1221211000 is an abundant number, since it is smaller than the sum of its proper divisors (1641601160).

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

1221211000 is a wasteful number, since it uses less digits than its factorization.

1221211000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2233 (or 2219 counting only the distinct ones).

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

The square root of 1221211000 is about 34945.8295079685. The cubic root of 1221211000 is about 1068.8831622776.

Adding to 1221211000 its reverse (1121221), we get a palindrome (1222332221).

The spelling of 1221211000 in words is "one billion, two hundred twenty-one million, two hundred eleven thousand".