91781786790 has 48 divisors (see below), whose sum is σ = 239255797248. Its totient is φ = 24411230208.

The previous prime is 91781786779. The next prime is 91781786797. The reversal of 91781786790 is 9768718719.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91781786797) 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, 1296859 + ... + 1365798.

It is an arithmetic number, because the mean of its divisors is an integer number (4984495776).

Almost surely, 2^91781786790 is an apocalyptic number.

91781786790 is a gapful number since it is divisible by the number (90) formed by its first and last digit.

91781786790 is an abundant number, since it is smaller than the sum of its proper divisors (147474010458).

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

91781786790 is a wasteful number, since it uses less digits than its factorization.

91781786790 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2663053 (or 2663050 counting only the distinct ones).

The product of its (nonzero) digits is 10668672, while the sum is 63.

The spelling of 91781786790 in words is "ninety-one billion, seven hundred eighty-one million, seven hundred eighty-six thousand, seven hundred ninety".