91729987 has 4 divisors (see below), whose sum is σ = 94893120. Its totient is φ = 88566856.

The previous prime is 91729969. The next prime is 91729991. The reversal of 91729987 is 78992719.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 78992719 = 13 ⋅6076363.

It is a cyclic number.

It is not a de Polignac number, because 91729987 - 2¹⁵ = 91697219 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (91729387) 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, 1581523 + ... + 1581580.

It is an arithmetic number, because the mean of its divisors is an integer number (23723280).

Almost surely, 2^91729987 is an apocalyptic number.

91729987 is a deficient number, since it is larger than the sum of its proper divisors (3163133).

91729987 is a wasteful number, since it uses less digits than its factorization.

91729987 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3163132.

The product of its digits is 571536, while the sum is 52.

The square root of 91729987 is about 9577.5773032641. The cubic root of 91729987 is about 450.9936675922.

The spelling of 91729987 in words is "ninety-one million, seven hundred twenty-nine thousand, nine hundred eighty-seven".