91843837821 has 10 divisors (see below), whose sum is σ = 137198819582. Its totient is φ = 61229225160.

The previous prime is 91843837807. The next prime is 91843837831. The reversal of 91843837821 is 12873834819.

It is a happy number.

91843837821 is a `hidden beast` number, since 9 + 184 + 383 + 7 + 82 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 80653160025 + 11190677796 = 283995^2 + 105786^2 .

It is not a de Polignac number, because 91843837821 - 2⁷ = 91843837693 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 (91843837801) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 566937190 + ... + 566937351.

Almost surely, 2^91843837821 is an apocalyptic number.

It is an amenable number.

91843837821 is a deficient number, since it is larger than the sum of its proper divisors (45354981761).

91843837821 is a wasteful number, since it uses less digits than its factorization.

91843837821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1133874553 (or 1133874544 counting only the distinct ones).

The product of its digits is 2322432, while the sum is 54.

The spelling of 91843837821 in words is "ninety-one billion, eight hundred forty-three million, eight hundred thirty-seven thousand, eight hundred twenty-one".