91521440 has 48 divisors (see below), whose sum is σ = 218485512. Its totient is φ = 36225024.

The previous prime is 91521431. The next prime is 91521467. The reversal of 91521440 is 4412519.

It can be written as a sum of positive squares in 4 ways, for example, as 86341264 + 5180176 = 9292^2 + 2276^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12572 + ... + 18468.

Almost surely, 2^91521440 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 91521440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (109242756).

91521440 is an abundant number, since it is smaller than the sum of its proper divisors (126964072).

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

91521440 is a wasteful number, since it uses less digits than its factorization.

91521440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6009 (or 6001 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 26.

The square root of 91521440 is about 9566.6838559660. The cubic root of 91521440 is about 450.6516320665.

Adding to 91521440 its reverse (4412519), we get a palindrome (95933959).

The spelling of 91521440 in words is "ninety-one million, five hundred twenty-one thousand, four hundred forty".