91649790981890 has 16 divisors (see below), whose sum is σ = 165923205410808. Its totient is φ = 36448009360896.

The previous prime is 91649790981767. The next prime is 91649790981913. The reversal of 91649790981890 is 9818909794619.

It can be written as a sum of positive squares in 4 ways, for example, as 91339632209329 + 310158772561 = 9557177^2 + 556919^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 26488377167 + ... + 26488380626.

Almost surely, 2^{91649790981890} is an apocalyptic number.

91649790981890 is a deficient number, since it is larger than the sum of its proper divisors (74273414428918).

91649790981890 is a wasteful number, since it uses less digits than its factorization.

91649790981890 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52976757973.

The product of its (nonzero) digits is 634894848, while the sum is 80.

The spelling of 91649790981890 in words is "ninety-one trillion, six hundred forty-nine billion, seven hundred ninety million, nine hundred eighty-one thousand, eight hundred ninety".