91561890 has 96 divisors (see below), whose sum is σ = 257731200. Its totient is φ = 20756736.

The previous prime is 91561871. The next prime is 91561891. The reversal of 91561890 is 9816519.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (91561891) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 292374 + ... + 292686.

It is an arithmetic number, because the mean of its divisors is an integer number (2684700).

Almost surely, 2^91561890 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 91561890, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (128865600).

91561890 is an abundant number, since it is smaller than the sum of its proper divisors (166169310).

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

91561890 is a wasteful number, since it uses less digits than its factorization.

91561890 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 536 (or 529 counting only the distinct ones).

The product of its (nonzero) digits is 19440, while the sum is 39.

The square root of 91561890 is about 9568.7977301226. The cubic root of 91561890 is about 450.7180142302.

The spelling of 91561890 in words is "ninety-one million, five hundred sixty-one thousand, eight hundred ninety".