991427057 has 2 divisors, whose sum is σ = 991427058. Its totient is φ = 991427056.

The previous prime is 991427023. The next prime is 991427069. The reversal of 991427057 is 750724199.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 768342961 + 223084096 = 27719^2 + 14936^2 .

It is a cyclic number.

It is not a de Polignac number, because 991427057 - 2¹⁶ = 991361521 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 991426999 and 991427017.

It is not a weakly prime, because it can be changed into another prime (991427357) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 495713528 + 495713529.

It is an arithmetic number, because the mean of its divisors is an integer number (495713529).

Almost surely, 2^991427057 is an apocalyptic number.

It is an amenable number.

991427057 is a deficient number, since it is larger than the sum of its proper divisors (1).

991427057 is an equidigital number, since it uses as much as digits as its factorization.

991427057 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 158760, while the sum is 44.

The square root of 991427057 is about 31486.9347031431. The cubic root of 991427057 is about 997.1341470662.

The spelling of 991427057 in words is "nine hundred ninety-one million, four hundred twenty-seven thousand, fifty-seven".