91721636 has 12 divisors (see below), whose sum is σ = 163233840. Its totient is φ = 45083400.

The previous prime is 91721629. The next prime is 91721657. The reversal of 91721636 is 63612719.

It is a junction number, because it is equal to n+sod(n) for n = 91721596 and 91721605.

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, 194090 + ... + 194561.

It is an arithmetic number, because the mean of its divisors is an integer number (13602820).

Almost surely, 2^91721636 is an apocalyptic number.

It is an amenable number.

91721636 is a deficient number, since it is larger than the sum of its proper divisors (71512204).

91721636 is a wasteful number, since it uses less digits than its factorization.

91721636 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 388714 (or 388712 counting only the distinct ones).

The product of its digits is 13608, while the sum is 35.

The square root of 91721636 is about 9577.1413271393. The cubic root of 91721636 is about 450.9799811830.

The spelling of 91721636 in words is "ninety-one million, seven hundred twenty-one thousand, six hundred thirty-six".