1891172640 has 144 divisors (see below), whose sum is σ = 6929883072. Its totient is φ = 432262656.

The previous prime is 1891172627. The next prime is 1891172641. The reversal of 1891172640 is 462711981.

It is not an unprimeable number, because it can be changed into a prime (1891172641) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 16684 + ... + 63723.

It is an arithmetic number, because the mean of its divisors is an integer number (48124188).

Almost surely, 2^1891172640 is an apocalyptic number.

1891172640 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 1891172640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3464941536).

1891172640 is an abundant number, since it is smaller than the sum of its proper divisors (5038710432).

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

1891172640 is a wasteful number, since it uses less digits than its factorization.

1891172640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 80439 (or 80424 counting only the distinct ones).

The product of its (nonzero) digits is 24192, while the sum is 39.

The square root of 1891172640 is about 43487.6147885809. The cubic root of 1891172640 is about 1236.6412399345.

The spelling of 1891172640 in words is "one billion, eight hundred ninety-one million, one hundred seventy-two thousand, six hundred forty".