91539721 has 8 divisors (see below), whose sum is σ = 112664384. Its totient is φ = 72426960.

The previous prime is 91539719. The next prime is 91539731. The reversal of 91539721 is 12793519.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 91539721 - 2¹ = 91539719 is a prime.

It is not an unprimeable number, because it can be changed into a prime (91539731) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 502875 + ... + 503056.

It is an arithmetic number, because the mean of its divisors is an integer number (14083048).

Almost surely, 2^91539721 is an apocalyptic number.

91539721 is a gapful number since it is divisible by the number (91) formed by its first and last digit.

It is an amenable number.

91539721 is a deficient number, since it is larger than the sum of its proper divisors (21124663).

91539721 is a wasteful number, since it uses less digits than its factorization.

91539721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1005951.

The product of its digits is 17010, while the sum is 37.

The square root of 91539721 is about 9567.6392595039. The cubic root of 91539721 is about 450.6816352877.

The spelling of 91539721 in words is "ninety-one million, five hundred thirty-nine thousand, seven hundred twenty-one".