91550021831 has 4 divisors (see below), whose sum is σ = 92014742952. Its totient is φ = 91085300712.

The previous prime is 91550021747. The next prime is 91550021861. The reversal of 91550021831 is 13812005519.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 91550021831 - 2³⁰ = 90476280007 is a prime.

It is a super-2 number, since 2×91550021831² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 91550021791 and 91550021800.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91550021861) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 232360265 + ... + 232360658.

It is an arithmetic number, because the mean of its divisors is an integer number (23003685738).

Almost surely, 2^91550021831 is an apocalyptic number.

91550021831 is a deficient number, since it is larger than the sum of its proper divisors (464721121).

91550021831 is a wasteful number, since it uses less digits than its factorization.

91550021831 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 464721120.

The product of its (nonzero) digits is 10800, while the sum is 35.

The spelling of 91550021831 in words is "ninety-one billion, five hundred fifty million, twenty-one thousand, eight hundred thirty-one".