1891687890 has 64 divisors (see below), whose sum is σ = 4693312512. Its totient is φ = 487468800.

The previous prime is 1891687879. The next prime is 1891687927. The reversal of 1891687890 is 987861981.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 1891687890.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1015560 + ... + 1017420.

It is an arithmetic number, because the mean of its divisors is an integer number (73333008).

Almost surely, 2^1891687890 is an apocalyptic number.

1891687890 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 1891687890, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2346656256).

1891687890 is an abundant number, since it is smaller than the sum of its proper divisors (2801624622).

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

1891687890 is a wasteful number, since it uses less digits than its factorization.

1891687890 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2995.

The product of its (nonzero) digits is 1741824, while the sum is 57.

The square root of 1891687890 is about 43493.5384856188. The cubic root of 1891687890 is about 1236.7535373750.

The spelling of 1891687890 in words is "one billion, eight hundred ninety-one million, six hundred eighty-seven thousand, eight hundred ninety".