91865521 has 4 divisors (see below), whose sum is σ = 100216944. Its totient is φ = 83514100.

The previous prime is 91865471. The next prime is 91865539. The reversal of 91865521 is 12556819.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 12556819 = 11 ⋅1141529.

It is a cyclic number.

It is not a de Polignac number, because 91865521 - 2⁹ = 91865009 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (91865021) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4175695 + ... + 4175716.

It is an arithmetic number, because the mean of its divisors is an integer number (25054236).

Almost surely, 2^91865521 is an apocalyptic number.

It is an amenable number.

91865521 is a deficient number, since it is larger than the sum of its proper divisors (8351423).

91865521 is a wasteful number, since it uses less digits than its factorization.

91865521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8351422.

The product of its digits is 21600, while the sum is 37.

The square root of 91865521 is about 9584.6502805267. The cubic root of 91865521 is about 451.2156774922.

The spelling of 91865521 in words is "ninety-one million, eight hundred sixty-five thousand, five hundred twenty-one".