91661587 has 2 divisors, whose sum is σ = 91661588. Its totient is φ = 91661586.

The previous prime is 91661533. The next prime is 91661593. The reversal of 91661587 is 78516619.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-91661587 is a prime.

It is not a weakly prime, because it can be changed into another prime (91661597) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45830793 + 45830794.

It is an arithmetic number, because the mean of its divisors is an integer number (45830794).

Almost surely, 2^91661587 is an apocalyptic number.

91661587 is a deficient number, since it is larger than the sum of its proper divisors (1).

91661587 is an equidigital number, since it uses as much as digits as its factorization.

91661587 is an evil number, because the sum of its binary digits is even.

The product of its digits is 90720, while the sum is 43.

The square root of 91661587 is about 9574.0057969483. The cubic root of 91661587 is about 450.8815427263.

The spelling of 91661587 in words is "ninety-one million, six hundred sixty-one thousand, five hundred eighty-seven".