91522721 has 4 divisors (see below), whose sum is σ = 91661844. Its totient is φ = 91383600.

The previous prime is 91522703. The next prime is 91522729. The reversal of 91522721 is 12722519.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12722519 = 23 ⋅553153.

It can be written as a sum of positive squares in 2 ways, for example, as 52635025 + 38887696 = 7255^2 + 6236^2 .

It is a cyclic number.

It is not a de Polignac number, because 91522721 - 2¹⁰ = 91521697 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (91522729) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 68570 + ... + 69891.

It is an arithmetic number, because the mean of its divisors is an integer number (22915461).

Almost surely, 2^91522721 is an apocalyptic number.

It is an amenable number.

91522721 is a deficient number, since it is larger than the sum of its proper divisors (139123).

91522721 is a wasteful number, since it uses less digits than its factorization.

91522721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 139122.

The product of its digits is 2520, while the sum is 29.

The square root of 91522721 is about 9566.7508068309. The cubic root of 91522721 is about 450.6537346050.

The spelling of 91522721 in words is "ninety-one million, five hundred twenty-two thousand, seven hundred twenty-one".