1991964520 has 256 divisors, whose sum is σ = 5780275200. Its totient is φ = 600929280.

The previous prime is 1991964517. The next prime is 1991964529. The reversal of 1991964520 is 254691991.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (1991964529) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 14330611 + ... + 14330749.

It is an arithmetic number, because the mean of its divisors is an integer number (22579200).

Almost surely, 2^1991964520 is an apocalyptic number.

1991964520 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 1991964520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2890137600).

1991964520 is an abundant number, since it is smaller than the sum of its proper divisors (3788310680).

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

1991964520 is a wasteful number, since it uses less digits than its factorization.

1991964520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 328 (or 324 counting only the distinct ones).

The product of its (nonzero) digits is 174960, while the sum is 46.

The square root of 1991964520 is about 44631.4297328687. The cubic root of 1991964520 is about 1258.2314399997.

The spelling of 1991964520 in words is "one billion, nine hundred ninety-one million, nine hundred sixty-four thousand, five hundred twenty".