1220021000 has 128 divisors (see below), whose sum is σ = 3135749760. Its totient is φ = 440608000.

The previous prime is 1220020987. The next prime is 1220021009. The reversal of 1220021000 is 1200221.

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

It is not an unprimeable number, because it can be changed into a prime (1220021009) 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, 2166719 + ... + 2167281.

It is an arithmetic number, because the mean of its divisors is an integer number (24498045).

Almost surely, 2^1220021000 is an apocalyptic number.

1220021000 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 1220021000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1567874880).

1220021000 is an abundant number, since it is smaller than the sum of its proper divisors (1915728760).

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

1220021000 is a wasteful number, since it uses less digits than its factorization.

1220021000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 792 (or 778 counting only the distinct ones).

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

The square root of 1220021000 is about 34928.7990059779. The cubic root of 1220021000 is about 1068.5358610220.

Adding to 1220021000 its reverse (1200221), we get a palindrome (1221221221).

The spelling of 1220021000 in words is "one billion, two hundred twenty million, twenty-one thousand".