91999487 has 2 divisors, whose sum is σ = 91999488. Its totient is φ = 91999486.

The previous prime is 91999469. The next prime is 91999493. The reversal of 91999487 is 78499919.

It is a strong prime.

It is an emirp because it is prime and its reverse (78499919) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 91999487 - 2²⁰ = 90950911 is a prime.

It is a plaindrome in base 16.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (91999447) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45999743 + 45999744.

It is an arithmetic number, because the mean of its divisors is an integer number (45999744).

Almost surely, 2^91999487 is an apocalyptic number.

91999487 is a deficient number, since it is larger than the sum of its proper divisors (1).

91999487 is an equidigital number, since it uses as much as digits as its factorization.

91999487 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1469664, while the sum is 56.

The square root of 91999487 is about 9591.6363046146. The cubic root of 91999487 is about 451.4349044642.

The spelling of 91999487 in words is "ninety-one million, nine hundred ninety-nine thousand, four hundred eighty-seven".