1991250828 has 144 divisors (see below), whose sum is σ = 5919513600. Its totient is φ = 564127200.

The previous prime is 1991250803. The next prime is 1991250841. The reversal of 1991250828 is 8280521991.

It is a congruent number.

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, 1616973 + ... + 1618203.

Almost surely, 2^1991250828 is an apocalyptic number.

1991250828 is a gapful number since it is divisible by the number (18) 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 1991250828, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2959756800).

1991250828 is an abundant number, since it is smaller than the sum of its proper divisors (3928262772).

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

1991250828 is a wasteful number, since it uses less digits than its factorization.

1991250828 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1393 (or 1374 counting only the distinct ones).

The product of its (nonzero) digits is 103680, while the sum is 45.

The square root of 1991250828 is about 44623.4336195681. The cubic root of 1991250828 is about 1258.0811533571.

The spelling of 1991250828 in words is "one billion, nine hundred ninety-one million, two hundred fifty thousand, eight hundred twenty-eight".