91810861 has 4 divisors (see below), whose sum is σ = 92030400. Its totient is φ = 91591324.

The previous prime is 91810853. The next prime is 91810879. The reversal of 91810861 is 16801819.

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.

It is a cyclic number.

It is not a de Polignac number, because 91810861 - 2³ = 91810853 is a prime.

It is a super-2 number, since 2×91810861² = 16858468395122642, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91810841) 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, 109141 + ... + 109978.

It is an arithmetic number, because the mean of its divisors is an integer number (23007600).

Almost surely, 2^91810861 is an apocalyptic number.

It is an amenable number.

91810861 is a deficient number, since it is larger than the sum of its proper divisors (219539).

91810861 is a wasteful number, since it uses less digits than its factorization.

91810861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 219538.

The product of its (nonzero) digits is 3456, while the sum is 34.

The square root of 91810861 is about 9581.7984220083. The cubic root of 91810861 is about 451.1261686033.

The spelling of 91810861 in words is "ninety-one million, eight hundred ten thousand, eight hundred sixty-one".