1221204140 has 72 divisors (see below), whose sum is σ = 2822975568. Its totient is φ = 443439360.

The previous prime is 1221204137. The next prime is 1221204167. The reversal of 1221204140 is 414021221.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 203219 + ... + 209141.

It is an arithmetic number, because the mean of its divisors is an integer number (39207994).

Almost surely, 2^1221204140 is an apocalyptic number.

1221204140 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 1221204140, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1411487784).

1221204140 is an abundant number, since it is smaller than the sum of its proper divisors (1601771428).

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

1221204140 is a wasteful number, since it uses less digits than its factorization.

1221204140 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6019 (or 6004 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 17.

The square root of 1221204140 is about 34945.7313559181. The cubic root of 1221204140 is about 1068.8811608347.

Adding to 1221204140 its reverse (414021221), we get a palindrome (1635225361).

The spelling of 1221204140 in words is "one billion, two hundred twenty-one million, two hundred four thousand, one hundred forty".