1991001222 has 240 divisors, whose sum is σ = 5608088640. Its totient is φ = 524670048.

The previous prime is 1991001217. The next prime is 1991001239. The reversal of 1991001222 is 2221001991.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 119 ways as a sum of consecutive naturals, for example, 6485193 + ... + 6485499.

It is an arithmetic number, because the mean of its divisors is an integer number (23367036).

Almost surely, 2^1991001222 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1991001222, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2804044320).

1991001222 is an abundant number, since it is smaller than the sum of its proper divisors (3617087418).

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

1991001222 is a wasteful number, since it uses less digits than its factorization.

1991001222 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 397 (or 381 counting only the distinct ones).

The product of its (nonzero) digits is 648, while the sum is 27.

The square root of 1991001222 is about 44620.6367278639. The cubic root of 1991001222 is about 1258.0285837659.

The spelling of 1991001222 in words is "one billion, nine hundred ninety-one million, one thousand, two hundred twenty-two".