1220991616 has 128 divisors (see below), whose sum is σ = 2783571840. Its totient is φ = 529182720.

The previous prime is 1220991613. The next prime is 1220991617. The reversal of 1220991616 is 6161990221.

It is a tau number, because it is divible by the number of its divisors (128).

It is not an unprimeable number, because it can be changed into a prime (1220991613) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2334331 + ... + 2334853.

It is an arithmetic number, because the mean of its divisors is an integer number (21746655).

Almost surely, 2^1220991616 is an apocalyptic number.

1220991616 is a gapful number since it is divisible by the number (16) 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 1220991616, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1391785920).

1220991616 is an abundant number, since it is smaller than the sum of its proper divisors (1562580224).

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

1220991616 is a wasteful number, since it uses less digits than its factorization.

1220991616 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 634 (or 622 counting only the distinct ones).

The product of its (nonzero) digits is 11664, while the sum is 37.

The square root of 1220991616 is about 34942.6904516524. The cubic root of 1220991616 is about 1068.8191520705.

The spelling of 1220991616 in words is "one billion, two hundred twenty million, nine hundred ninety-one thousand, six hundred sixteen".