991606237 has 2 divisors, whose sum is σ = 991606238. Its totient is φ = 991606236.

The previous prime is 991606211. The next prime is 991606241. The reversal of 991606237 is 732606199.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 989794521 + 1811716 = 31461^2 + 1346^2 .

It is a cyclic number.

It is not a de Polignac number, because 991606237 - 2¹⁵ = 991573469 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 991606193 and 991606202.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (991606537) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 495803118 + 495803119.

It is an arithmetic number, because the mean of its divisors is an integer number (495803119).

Almost surely, 2^991606237 is an apocalyptic number.

It is an amenable number.

991606237 is a deficient number, since it is larger than the sum of its proper divisors (1).

991606237 is an equidigital number, since it uses as much as digits as its factorization.

991606237 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 122472, while the sum is 43.

The square root of 991606237 is about 31489.7798817331. The cubic root of 991606237 is about 997.1942139273.

The spelling of 991606237 in words is "nine hundred ninety-one million, six hundred six thousand, two hundred thirty-seven".