91721008 has 20 divisors (see below), whose sum is σ = 178066728. Its totient is φ = 45768320.

The previous prime is 91720991. The next prime is 91721011. The reversal of 91721008 is 80012719.

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, 2835 + ... + 13837.

Almost surely, 2^91721008 is an apocalyptic number.

It is an amenable number.

91721008 is a deficient number, since it is larger than the sum of its proper divisors (86345720).

91721008 is a wasteful number, since it uses less digits than its factorization.

91721008 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11532 (or 11526 counting only the distinct ones).

The product of its (nonzero) digits is 1008, while the sum is 28.

The square root of 91721008 is about 9577.1085406818. The cubic root of 91721008 is about 450.9789519235.

The spelling of 91721008 in words is "ninety-one million, seven hundred twenty-one thousand, eight".