91211621660 has 12 divisors (see below), whose sum is σ = 191544405528. Its totient is φ = 36484648656.

The previous prime is 91211621623. The next prime is 91211621671. The reversal of 91211621660 is 6612611219.

It is a self number, because there is not a number n which added to its sum of digits gives 91211621660.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2280290522 + ... + 2280290561.

It is an arithmetic number, because the mean of its divisors is an integer number (15962033794).

Almost surely, 2^91211621660 is an apocalyptic number.

It is an amenable number.

91211621660 is an abundant number, since it is smaller than the sum of its proper divisors (100332783868).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

91211621660 is a wasteful number, since it uses less digits than its factorization.

91211621660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4560581092 (or 4560581090 counting only the distinct ones).

The product of its (nonzero) digits is 7776, while the sum is 35.

The spelling of 91211621660 in words is "ninety-one billion, two hundred eleven million, six hundred twenty-one thousand, six hundred sixty".