91217712501 has 6 divisors (see below), whose sum is σ = 131758918070. Its totient is φ = 60811808328.

The previous prime is 91217712499. The next prime is 91217712511. The reversal of 91217712501 is 10521771219.

It can be written as a sum of positive squares in only one way, i.e., 69564590001 + 21653122500 = 263751^2 + 147150^2 .

It is not a de Polignac number, because 91217712501 - 2¹ = 91217712499 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91217712511) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 5067650686 + ... + 5067650703.

Almost surely, 2^91217712501 is an apocalyptic number.

It is an amenable number.

91217712501 is a deficient number, since it is larger than the sum of its proper divisors (40541205569).

91217712501 is a wasteful number, since it uses less digits than its factorization.

91217712501 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10135301395 (or 10135301392 counting only the distinct ones).

The product of its (nonzero) digits is 8820, while the sum is 36.

The spelling of 91217712501 in words is "ninety-one billion, two hundred seventeen million, seven hundred twelve thousand, five hundred one".