1221127380 has 192 divisors, whose sum is σ = 4172636160. Its totient is φ = 294019200.

The previous prime is 1221127379. The next prime is 1221127387. The reversal of 1221127380 is 837211221.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221127387) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 991365 + ... + 992595.

It is an arithmetic number, because the mean of its divisors is an integer number (21732480).

Almost surely, 2^1221127380 is an apocalyptic number.

1221127380 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 1221127380, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2086318080).

1221127380 is an abundant number, since it is smaller than the sum of its proper divisors (2951508780).

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

1221127380 is a wasteful number, since it uses less digits than its factorization.

1221127380 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1427 (or 1419 counting only the distinct ones).

The product of its (nonzero) digits is 1344, while the sum is 27.

The square root of 1221127380 is about 34944.6330643205. The cubic root of 1221127380 is about 1068.8587651696.

The spelling of 1221127380 in words is "one billion, two hundred twenty-one million, one hundred twenty-seven thousand, three hundred eighty".