91621823 has 4 divisors (see below), whose sum is σ = 97011360. Its totient is φ = 86232288.

The previous prime is 91621787. The next prime is 91621837. The reversal of 91621823 is 32812619.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 32812619 = 7 ⋅4687517.

It is a cyclic number.

It is not a de Polignac number, because 91621823 - 2⁸ = 91621567 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 91621823.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91621843) 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, 2694743 + ... + 2694776.

It is an arithmetic number, because the mean of its divisors is an integer number (24252840).

Almost surely, 2^91621823 is an apocalyptic number.

91621823 is a deficient number, since it is larger than the sum of its proper divisors (5389537).

91621823 is a wasteful number, since it uses less digits than its factorization.

91621823 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5389536.

The product of its digits is 5184, while the sum is 32.

The square root of 91621823 is about 9571.9289069654. The cubic root of 91621823 is about 450.8163338514.

The spelling of 91621823 in words is "ninety-one million, six hundred twenty-one thousand, eight hundred twenty-three".