1221159780 has 48 divisors (see below), whose sum is σ = 3799165440. Its totient is φ = 325642464.

The previous prime is 1221159749. The next prime is 1221159799. The reversal of 1221159780 is 879511221.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (36).

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, 1130164 + ... + 1131243.

It is an arithmetic number, because the mean of its divisors is an integer number (79149280).

Almost surely, 2^1221159780 is an apocalyptic number.

1221159780 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1221159780 is an abundant number, since it is smaller than the sum of its proper divisors (2578005660).

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

1221159780 is a wasteful number, since it uses less digits than its factorization.

1221159780 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2261425 (or 2261417 counting only the distinct ones).

The product of its (nonzero) digits is 10080, while the sum is 36.

The square root of 1221159780 is about 34945.0966517479. The cubic root of 1221159780 is about 1068.8682183788.

The spelling of 1221159780 in words is "one billion, two hundred twenty-one million, one hundred fifty-nine thousand, seven hundred eighty".