91878021774 has 288 divisors, whose sum is σ = 261771374592. Its totient is φ = 22769683200.

The previous prime is 91878021757. The next prime is 91878021791. The reversal of 91878021774 is 47712087819.

It is an interprime number because it is at equal distance from previous prime (91878021757) and next prime (91878021791).

It is a self number, because there is not a number n which added to its sum of digits gives 91878021774.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 34500367 + ... + 34503029.

It is an arithmetic number, because the mean of its divisors is an integer number (908928384).

Almost surely, 2^91878021774 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 91878021774, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (130885687296).

91878021774 is an abundant number, since it is smaller than the sum of its proper divisors (169893352818).

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

91878021774 is a wasteful number, since it uses less digits than its factorization.

91878021774 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2804 (or 2790 counting only the distinct ones).

The product of its (nonzero) digits is 1580544, while the sum is 54.

The spelling of 91878021774 in words is "ninety-one billion, eight hundred seventy-eight million, twenty-one thousand, seven hundred seventy-four".