91215680 has 28 divisors (see below), whose sum is σ = 217208100. Its totient is φ = 36486144.

The previous prime is 91215653. The next prime is 91215689. The reversal of 91215680 is 8651219.

It can be written as a sum of positive squares in 2 ways, for example, as 66455104 + 24760576 = 8152^2 + 4976^2 .

It is a Harshad number since it is a multiple of its sum of digits (32).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91215689) 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, 142205 + ... + 142844.

Almost surely, 2^91215680 is an apocalyptic number.

It is an amenable number.

91215680 is an abundant number, since it is smaller than the sum of its proper divisors (125992420).

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

91215680 is a wasteful number, since it uses less digits than its factorization.

91215680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 285066 (or 285056 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 32.

The square root of 91215680 is about 9550.6900274273. The cubic root of 91215680 is about 450.1492180042.

Adding to 91215680 its reverse (8651219), we get a palindrome (99866899).

The spelling of 91215680 in words is "ninety-one million, two hundred fifteen thousand, six hundred eighty".