91331550 has 72 divisors (see below), whose sum is σ = 254499336. Its totient is φ = 24351840.

The previous prime is 91331509. The next prime is 91331567. The reversal of 91331550 is 5513319.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 8392 + ... + 15908.

It is an arithmetic number, because the mean of its divisors is an integer number (3534713).

Almost surely, 2^91331550 is an apocalyptic number.

91331550 is a gapful number since it is divisible by the number (90) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 91331550, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (127249668).

91331550 is an abundant number, since it is smaller than the sum of its proper divisors (163167786).

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

91331550 is a wasteful number, since it uses less digits than its factorization.

91331550 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7544 (or 7527 counting only the distinct ones).

The product of its (nonzero) digits is 2025, while the sum is 27.

The square root of 91331550 is about 9556.7541560930. The cubic root of 91331550 is about 450.3397434341.

Adding to 91331550 its reverse (5513319), we get a palindrome (96844869).

The spelling of 91331550 in words is "ninety-one million, three hundred thirty-one thousand, five hundred fifty".