91912039621 has 4 divisors (see below), whose sum is σ = 92001016492. Its totient is φ = 91823062752.

The previous prime is 91912039619. The next prime is 91912039643. The reversal of 91912039621 is 12693021919.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12693021919 = 29 ⋅437690411.

It can be written as a sum of positive squares in 2 ways, for example, as 44903729025 + 47008310596 = 211905^2 + 216814^2 .

It is a cyclic number.

It is not a de Polignac number, because 91912039621 - 2¹ = 91912039619 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91912009621) 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, 44486886 + ... + 44488951.

It is an arithmetic number, because the mean of its divisors is an integer number (23000254123).

Almost surely, 2^91912039621 is an apocalyptic number.

It is an amenable number.

91912039621 is a deficient number, since it is larger than the sum of its proper divisors (88976871).

91912039621 is a wasteful number, since it uses less digits than its factorization.

91912039621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 88976870.

The product of its (nonzero) digits is 52488, while the sum is 43.

The spelling of 91912039621 in words is "ninety-one billion, nine hundred twelve million, thirty-nine thousand, six hundred twenty-one".