1991123946 has 96 divisors (see below), whose sum is σ = 5231910528. Its totient is φ = 534251520.

The previous prime is 1991123909. The next prime is 1991123969. The reversal of 1991123946 is 6493211991.

It is a super-2 number, since 2×1991123946² = 7929149136669221832, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1462306 + ... + 1463666.

It is an arithmetic number, because the mean of its divisors is an integer number (54499068).

Almost surely, 2^1991123946 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1991123946, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2615955264).

1991123946 is an abundant number, since it is smaller than the sum of its proper divisors (3240786582).

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

1991123946 is a wasteful number, since it uses less digits than its factorization.

1991123946 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2076 (or 2073 counting only the distinct ones).

The product of its digits is 104976, while the sum is 45.

The square root of 1991123946 is about 44622.0118999581. The cubic root of 1991123946 is about 1258.0544312517.

The spelling of 1991123946 in words is "one billion, nine hundred ninety-one million, one hundred twenty-three thousand, nine hundred forty-six".