91551 has 4 divisors (see below), whose sum is σ = 122072. Its totient is φ = 61032.

The previous prime is 91541. The next prime is 91571. The reversal of 91551 is 15519.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 91551 - 2⁷ = 91423 is a prime.

It is a D-number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91541) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 15256 + ... + 15261.

It is an arithmetic number, because the mean of its divisors is an integer number (30518).

2⁹¹⁵⁵¹ is an apocalyptic number.

91551 is a deficient number, since it is larger than the sum of its proper divisors (30521).

91551 is a wasteful number, since it uses less digits than its factorization.

91551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30520.

The product of its digits is 225, while the sum is 21.

The square root of 91551 is about 302.5739579012. The cubic root of 91551 is about 45.0700144664.

It can be divided in two parts, 915 and 51, that multiplied together give a triangular number (46665 = T₃₀₅).

The spelling of 91551 in words is "ninety-one thousand, five hundred fifty-one".