1221220000 has 480 divisors, whose sum is σ = 4099987584. Its totient is φ = 345600000.

The previous prime is 1221219971. The next prime is 1221220001. The reversal of 1221220000 is 221221.

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

It is not an unprimeable number, because it can be changed into a prime (1221220001) by changing a digit.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 20019970 + ... + 20020030.

Almost surely, 2^1221220000 is an apocalyptic number.

1221220000 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 1221220000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2049993792).

1221220000 is an abundant number, since it is smaller than the sum of its proper divisors (2878767584).

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

1221220000 is a wasteful number, since it uses less digits than its factorization.

1221220000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 122 (or 99 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 10.

The square root of 1221220000 is about 34945.9582784619. The cubic root of 1221220000 is about 1068.8857880660.

Adding to 1221220000 its reverse (221221), we get a palindrome (1221441221).

It can be divided in two parts, 122 and 1220000, that multiplied together give a square (148840000 = 12200²).

The spelling of 1221220000 in words is "one billion, two hundred twenty-one million, two hundred twenty thousand".