91151681980921 has 3 divisors (see below), whose sum is σ = 91151691528261. Its totient is φ = 91151672433582.

The previous prime is 91151681980913. The next prime is 91151681980949. The reversal of 91151681980921 is 12908918615119.

The square root of 91151681980921 is 9547339.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is not a de Polignac number, because 91151681980921 - 2³ = 91151681980913 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 91151681980921.

It is not an unprimeable number, because it can be changed into a prime (91151681980981) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 4773670 + ... + 14321008.

It is an arithmetic number, because the mean of its divisors is an integer number (30383897176087).

Almost surely, 2^{91151681980921} is an apocalyptic number.

91151681980921 is the 9547339-th square number.

91151681980921 is the 4773670-th centered octagonal number.

It is an amenable number.

91151681980921 is a deficient number, since it is larger than the sum of its proper divisors (9547340).

91151681980921 is an frugal number, since it uses more digits than its factorization.

91151681980921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19094678 (or 9547339 counting only the distinct ones).

The product of its (nonzero) digits is 2799360, while the sum is 61.

The spelling of 91151681980921 in words is "ninety-one trillion, one hundred fifty-one billion, six hundred eighty-one million, nine hundred eighty thousand, nine hundred twenty-one".