991900937 has 2 divisors, whose sum is σ = 991900938. Its totient is φ = 991900936.

The previous prime is 991900867. The next prime is 991900939. The reversal of 991900937 is 739009199.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 784224016 + 207676921 = 28004^2 + 14411^2 .

It is a cyclic number.

It is not a de Polignac number, because 991900937 - 2²² = 987706633 is a prime.

Together with 991900939, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 991900891 and 991900900.

It is not a weakly prime, because it can be changed into another prime (991900939) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 495950468 + 495950469.

It is an arithmetic number, because the mean of its divisors is an integer number (495950469).

Almost surely, 2^991900937 is an apocalyptic number.

It is an amenable number.

991900937 is a deficient number, since it is larger than the sum of its proper divisors (1).

991900937 is an equidigital number, since it uses as much as digits as its factorization.

991900937 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 137781, while the sum is 47.

The square root of 991900937 is about 31494.4588300863. The cubic root of 991900937 is about 997.2929910481.

The spelling of 991900937 in words is "nine hundred ninety-one million, nine hundred thousand, nine hundred thirty-seven".