91930021 has 4 divisors (see below), whose sum is σ = 91962700. Its totient is φ = 91897344.

The previous prime is 91929997. The next prime is 91930043. The reversal of 91930021 is 12003919.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12003919 = 179 ⋅67061.

It can be written as a sum of positive squares in 2 ways, for example, as 31696900 + 60233121 = 5630^2 + 7761^2 .

It is a cyclic number.

It is not a de Polignac number, because 91930021 - 2¹¹ = 91927973 is a prime.

It is a super-3 number, since 3×91930021³ (a number of 25 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a pancake number, because a pancake can be divided into 91930021 parts by 13559 straight cuts.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91930051) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 11676 + ... + 17893.

It is an arithmetic number, because the mean of its divisors is an integer number (22990675).

Almost surely, 2^91930021 is an apocalyptic number.

It is an amenable number.

91930021 is a deficient number, since it is larger than the sum of its proper divisors (32679).

91930021 is a wasteful number, since it uses less digits than its factorization.

91930021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32678.

The product of its (nonzero) digits is 486, while the sum is 25.

The square root of 91930021 is about 9588.0144451289. The cubic root of 91930021 is about 451.3212542898.

The spelling of 91930021 in words is "ninety-one million, nine hundred thirty thousand, twenty-one".