1221799680 has 144 divisors (see below), whose sum is σ = 4335814560. Its totient is φ = 325804032.

The previous prime is 1221799679. The next prime is 1221799729. The reversal of 1221799680 is 869971221.

It is a tau number, because it is divible by the number of its divisors (144).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

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, 16884 + ... + 52236.

Almost surely, 2^1221799680 is an apocalyptic number.

1221799680 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 1221799680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2167907280).

1221799680 is an abundant number, since it is smaller than the sum of its proper divisors (3114014880).

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

1221799680 is an equidigital number, since it uses as much as digits as its factorization.

1221799680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35383 (or 35363 counting only the distinct ones).

The product of its (nonzero) digits is 108864, while the sum is 45.

The square root of 1221799680 is about 34954.2512435898. The cubic root of 1221799680 is about 1069.0548850078.

The spelling of 1221799680 in words is "one billion, two hundred twenty-one million, seven hundred ninety-nine thousand, six hundred eighty".