991286057 has 2 divisors, whose sum is σ = 991286058. Its totient is φ = 991286056.

The previous prime is 991286027. The next prime is 991286117. The reversal of 991286057 is 750682199.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 608066281 + 383219776 = 24659^2 + 19576^2 .

It is an emirp because it is prime and its reverse (750682199) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 991286057 - 2¹⁴ = 991269673 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (991286017) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 495643028 + 495643029.

It is an arithmetic number, because the mean of its divisors is an integer number (495643029).

Almost surely, 2^991286057 is an apocalyptic number.

It is an amenable number.

991286057 is a deficient number, since it is larger than the sum of its proper divisors (1).

991286057 is an equidigital number, since it uses as much as digits as its factorization.

991286057 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 272160, while the sum is 47.

The square root of 991286057 is about 31484.6955996084. The cubic root of 991286057 is about 997.0868742724.

The spelling of 991286057 in words is "nine hundred ninety-one million, two hundred eighty-six thousand, fifty-seven".